Magnetic Behavior of Carboxylate and -Diketonate Lanthanide ... - MDPI

magnetochemistry Article

Magnetic Behavior of Carboxylate and β-Diketonate Lanthanide Complexes Containing Stable Organometallic Moieties in the Core-Forming Ligand Nikolay N. Efimov *, Pavel S. Koroteev *, Andrey V. Gavrikov, Andrey B. Ilyukhin, Zhanna V. Dobrokhotova and Vladimir M. Novotortsev N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky prosp. 31, 119991 Moscow, Russia; [email protected] (A.V.G.); [email protected] (A.B.I.); [email protected] (Z.V.D.); [email protected] (V.M.N.) * Correspondence: [email protected] (N.N.E.); [email protected] (P.S.K.); Tel.: +7-495-955-48-05 (N.N.E. & P.S.K.) Academic Editor: Floriana Tuna Received: 28 July 2016; Accepted: 28 September 2016; Published: 10 October 2016

Abstract: Information concerning the structures of compounds of rare earth elements with carboxylic acids and a β-diketone containing stable organometallic moieties that we obtained previously is presented. Additional results for 15 complexes with the [Gd2 O2 ] core allowed confirming and improving the correlation between JGd–Gd0 and the Gd. . . Gd distance for complexes of this type that we found earlier. For the first time, dc and ac magnetic measurements were carried out for the formerly-described complex [Dy2 (O2 CCym)4 (NO3 )2 (DMSO)4 ] (2), Cym = (η5-C5H4)Mn(CO)3), and two new binuclear complexes, namely [Dy2(O2CFc)4(NO3)2(DMSO)4] (3), and [Dy2 (O2 CFc)6 (DMSO)2 (H2 O)2 ] (4), Fc = (η5 -C5 H4 )Fe(η5 -C5 H5 )). For binuclear [Dy2 (O2 CCym)6 (DMSO)4 ] (1), as well as for a 1D-polymer [Dy(O2 CCym)(acac)2 (H2 O)]n (6), ac magnetic measurements were carried out more precisely. The characteristics of a single-molecule magnet and of a single-chain magnet were determined for Complexes 2 and 6, respectively. Keywords: lanthanide complex; cymantrenecarboxylate; ferrocenecarboxylate; ferrocenoylacetonate; magneto-structural correlation; slow magnetic relaxation; molecular magnetism; coordination polymer

1. Introduction Single-molecule magnets (SMM) are molecule-scale objects that demonstrate properties characteristic of bulk magnetic materials. In compounds of this kind, the classical phenomenon of residual magnetization retention is based on magnetic anisotropy on molecular and atomic levels. The majority of currently-known SMMs are the coordination compounds whose molecules contain a few metal ions with rather a large number of unpaired electrons and can retain residual magnetization for some time at very low temperatures. Compounds of this kind may be regarded as elements of high-density magnetic memory, i.e., promising components for data storage. A powerful impetus to the developments in this field was given by studies of the magnetic properties of the {Mn12 } cluster [1,2]. Currently, close attention of researchers is given to coordination compounds of lanthanides in the context of molecular magnetism. The interest in coordination compounds of rare earth elements (REE) is currently rather high [3,4], primarily due to their unique magnetic properties [5–9]. Among them, considerable attention is paid to β-diketonate and carboxylate derivatives. The latter class of compounds is characterized by a wide structural variety that is mainly reached due to the ability of carboxylic groups to show various structural functions. It is also attained by incorporation of additional ligands [10]. The most Magnetochemistry 2016, 2, 38; doi:10.3390/magnetochemistry2040038

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approach to the design of lanthanide-containing SMM involves the use of ligand field symmetry to approach to the design of involves theinvolves use of ligand field to 3+ ions [11].SMM popular approach to the design SMM thespecifics use ofsymmetry ligand field increase the anisotropy of lanthanide-containing isolatedofLnlanthanide-containing At the same time, beside the of the local 3+ same 3+ ions increase the anisotropy of isolated Ln [11]. At the time, beside the specifics of the local 3+ symmetry to increase the anisotropy of isolated Ln ions [11]. At the same time, beside the symmetry of Dy , a considerable role may belong to the ligand nature (electrostatic aspect) [12]. 3+ , abelong 3+ symmetry Dy , a considerable role to the ligand nature (electrostatic [12]. specifics the local symmetry of Dymay considerable role may belong to theis ligand nature Therefore,ofof the suggestion of new core-forming ligands for directed design of SMM ofaspect) undoubted Therefore, the suggestion of new core-forming ligands for directed design of SMM is of undoubted (electrostatic aspect) [12]. Therefore, the suggestion of new core-forming ligands for directed design of interest. interest. SMMAn is of undoubted interest. interesting, but insufficiently studied group among carboxylate and β-diketonate lanthanide An interesting, butcomplexes insufficiently studied among carboxylate and β-diketonate lanthanide interesting, insufficiently β-diketonate lanthanide derivatives comprises in which thegroup core-forming (carboxylate/β-diketone) ligand contains derivatives comprises complexes in which the core-forming (carboxylate/β-diketone) ligand contains 5 derivatives comprises complexes in which the core-forming (carboxylate/β-diketone) ligand stable organometallic moieties, viz. derivatives of ferrocene (bis(η -cyclopentadienyl)iron, (η55 5 5 stable organometallic moieties, viz. derivatives of ferrocene (bis(η(bis(η -cyclopentadienyl)iron, 5-cyclopentadienyltricarbonylmanganese, 5-C5H5)Mn(CO)3), (η contains stable moieties, viz. derivatives of ferrocene -cyclopentadienyl)iron, С5Н5)2Fe), and organometallic cymantrene (η (η the5 5 5 5 5 С 5Н 5)5 2Fe), and cymantrene -cyclopentadienyltricarbonylmanganese, (η -C 5H 5)Mn(CO) 3), the (η -C H5 )2 Fe), and cymantrene (η -cyclopentadienyltricarbonylmanganese, (η -C 5 H5 )Mn(CO) 3 ), derivatives of cymantreneand(ηferrocene-carboxylic acids in particular (Scheme 1). derivatives of cymantreneandand ferrocene-carboxylic acids in particular (Scheme 1). 1). the derivatives of cymantreneferrocene-carboxylic acids in particular (Scheme COOH COOH COOH COOH

Mn OC Mn CO CO CO OC CO (a) (a)

Fe Fe

(b) (b)

Scheme 1. (a) cymantrenecarboxylic acid (CymCO2H); (b) ferrocenecarboxylic acid (FcCO2H). Scheme (CymCO22H); Scheme 1. 1. (a) (a) cymantrenecarboxylic cymantrenecarboxylic acid acid (CymCO H); (b) (b) ferrocenecarboxylic ferrocenecarboxylic acid acid (FcCO (FcCO22H). H).

These ligands are bulky; they also have a highly polarizable π-system. Therefore, both steric and These ligands are also highly polarizable π-system. both steric electronic play a they significant roleaa in metal carboxylates/β-diketonates. Such compounds Theseeffects ligandsmay are bulky; bulky; they also have have highly polarizable π-system. Therefore, Therefore, both steric and and electronic effects may play a significant role in metal carboxylates/β-diketonates. Such compounds also represent original of heterometallic since they are potentially able to electronic effectsthe may play a type significant role in metal complexes, carboxylates/β-diketonates. Such compounds also represent the original type of heterometallic complexes, they are potentially able to combine specific properties of the metal ion andcomplexes, of the organometallic fragment. For able example, in the also represent the original type of heterometallic since since they are potentially to combine combine specific properties of the of the organometallic fragment. Fortoexample, in the aspect of magnetic themetal reversible conversion of fragment. the ferrocenyl group specific properties ofproperties, the metal ion and ofion theand organometallic For example, inparamagnetic the aspect of aspect of magnetic properties, the reversible conversion of the ferrocenyl group to paramagnetic ferrocenium in the solid state of ferrocenecarboxylates is of interest magnetic properties, the reversible conversion of the ferrocenyl group[13,14]. to paramagnetic ferrocenium in ferrocenium inofthe solid state of ferrocenecarboxylates is of interestand [13,14]. Thisstate paper provides a review of our (2011–2016) new synthetic and structural the solid ferrocenecarboxylates is of previous interest [13,14]. This paper provides a review of our previous (2011–2016) and new synthetic and structural results studies on the magnetic behavior(2011–2016) of cymantreneferrocene-carboxylates of Thisofpaper provides a review of our previous and newand synthetic and structural results results of studies on the magnetic behavior of cymantreneand ferrocene-carboxylates of dysprosium. of studies on the magnetic behavior of cymantrene- and ferrocene-carboxylates of dysprosium. dysprosium. 2. Results Resultsand andDiscussion Discussion 2. Results and Discussion no information about cymantrenecarboxylates of rare earth and their magnetic First ofofall,all, no information about cymantrenecarboxylates of metals rare earth metals and First of all, no information about cymantrenecarboxylates of rare earth metals and their magnetic properties was properties available was before our first publication To date, have we obtained their magnetic available before our first [15]. publication [15]. we To date, have properties was available our first publication [15].[15–18] To date, we have obtained cymantrenecarboxylates withbefore various structures, both binuclear and[15–18] polymeric obtained cymantrenecarboxylates with various structures, both binuclear and complexes polymeric cymantrenecarboxylates with various structures, both binuclear [15–18] and polymeric complexes [19–21]. [19–21]. complexes [19–21]. The first complexes of this type that we obtained included two similar series of heteroleptic 2 -O 0 -O CCym) 22-O The first complexes this type that [Ln we obtained included two similar series of heteroleptic 2-O cymantrenecarboxylates light lanthanides, [Ln 2(μ-О,η 2CCym) 2(μ 2-О,О′-O 2(η -О ССym)22LL44] cymantrenecarboxylates ofofof light lanthanides, 2 (µ-O,η 2 CCym) 2 (µ 2 -O,O 2 2CCym) 2 (η 22CCym) 2 2 cymantrenecarboxylates lanthanides, [Ln2(μ-О,η -O CCym) -О,О′-O 2L4] moleculesofof oflight volatile tetrahydrofuran (Ln Nd,nn==2(μ 0;2Ln Ln == Gd, Gd,2CCym) Eu, nn ==2(η THF) [15] nL, containing molecules volatile tetrahydrofuran (Ln ==2Nd, 0; Eu, 1; -О L =2ССym) nL, containing molecules of volatile tetrahydrofuran (Ln = Nd, n = 0; Ln = Gd, Eu, n = 1; L = THF) [15] or pyridine (Ln == Pr, Pr, Sm, Sm, Eu, Eu, Gd, Gd, nn ==2,2,LL==Py) Py)[16] [16]asasneutral neutralligands. ligands.The Theobtained obtainedcomplexes complexeshad hada or pyridine (Ln = Pr,typical Sm, Eu, Gd, n = 2, L =carboxylates Py) [16] as neutral ligands. The obtained complexes had a structure ofof lanthanide (Figure 1).1). abinuclear binuclear structure typical lanthanide carboxylates (Figure binuclear structure typical of lanthanide carboxylates (Figure 1).

Figure 1. Molecular structure of [Ln2(μ-О,η2-O2CCym)2(μ2-О,О′-O2CCym)2(η2-О2ССym)2(THF)4]. Figure 1. Molecular structure of [Ln2 (µ-O,η2 -O22 CCym)2 (µ2 -O,O0 -O2 CCym)2 (η22-O2 CCym)2 (THF)4 ]. Figure 1. Molecular structure of [Ln 2(μ2-О,О′-O2CCym)2(η -О2ССym)2(THF)4]. Reproduced from the the work work [15] with with the2(μ-О,η change-O in2CCym) appearance. Reproduced from [15] the change in appearance. Reproduced from the work [15] with the change in appearance.

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Furthermore, a series of binuclear complexes that contained relatively low volatile DMSO as the 0relatively 2volatile Furthermore, series of of binuclear complexes that contained contained low DMSO as the the neutral ligand was obtained, namely [Ln2complexes (µ-O,η2 -O2 CCym) -O2 CCym)low -O2 CCym) 2 (µ2 -O,Orelatively 2 (η volatile 2 (DMSO) 4 ]; Furthermore, aa series binuclear that DMSO as 2-O2CCym)2(μ2-О,О′-O2CCym)2(η2-О2ССym)2(DMSO)4]; neutral ligand was obtained, namely [Ln 2 (μ-О,η Ln = Ce,ligand Nd, Eu, Gdobtained, [17]; Ln = Tb, Dy[Ln [18]. neutral was namely 2(μ-О,η2-O2CCym)2(μ2-О,О′-O2CCym)2(η2-О2ССym)2(DMSO)4]; Ln = Ce, Nd, Eu, Gd [17]; Ln = Tb, Dy [18]. The first representatives of lanthanide cymantrenecarboxylates with the ratio Ln:Mn = 1:2 were Ln = Ce, Nd, Eu, Gd [17]; Ln = Tb, Dy [18]. 2 -O CCym) (η2 -NOwith 2the The first representatives of lanthanide cymantrenecarboxylates ratio2 ]Ln:Mn Ln:Mn 1:2 were binuclear compounds [Ln (µ -O CCym) (µ-O,η -DME) (Ln = Pr, Eu,were Gd, 2 2of lanthanide 2 2 cymantrenecarboxylates 2 2 3 )2 (η the The first representatives with ratio == 1:2 2-O2CCym)2(η2-NO3)02(η2-DME)2] (Ln 2 binuclear compounds [Ln 2 (μ 2 -O 2 CCym) 2 (μ-О,η = Pr, Eu, Gd, Tb, 2-O2and Tb, Dy, Ho, Er; DME (1,2-dimethoxyethane)) [Ln22(η (µ22-NO -O,O CCym)2]4 (Ln (η -NO 2 (DMSO) 4] binuclear compounds [Ln2(μ2-O2CCym)2(μ-О,η[19] CCym) 3)2-O (η22-DME) = Pr,3 )Eu, Gd, Tb, 2 Dy, Ho, Er; DME (1,2-dimethoxyethane)) [19] and [Ln 2] (μ 2-О,О′-O2CCym) 4(η2 -NО 3)2(DMSO) 4] (Ln = (Ln = Tb, Dy) [18]. The [Ln (O CCym) (NO ) (DME) complexes are built similarly to binuclear 2 2 4 [19] 3 2and [Ln22(μ2-О,О′-O2CCym)4(η -NО3)2(DMSO)4] (Ln = Dy, Ho, Er; DME (1,2-dimethoxyethane)) Tb, Dy) Dy) [18]. [18].with The [Ln [Ln 2(O2CCym)4(NO (DME)22]]except complexes are built similarly to binuclear binuclear complexes complexes THF, and33))22DMSO, thatare thebuilt rolesimilarly of chelating anions complexes is played Tb, The 2(Opyridine 2CCym)4(NO (DME) complexes to with THF, pyridine and DMSO, except that the role of chelating anions is played by nitrate ions, by nitrate ions, whereas chelate molecules are theanions neutral ligands. another with THF, pyridine and DMSO, except that the of roleDME of chelating is played by Yet nitrate ions, whereas chelate molecules of DME DME are the the neutral ligands. Yet another type of of compound compound with with the the type of chelate compound with of the Ln:Mn ratio of 1:2ligands. is the Yet mixed acetate-cymantrenecarboxylate whereas molecules are neutral another type Ln:Mn ratio of 1:2 is the mixed acetate-cymantrenecarboxylate complexes [20]. In the case of heavier complexes [20]. Inthe the caseacetate-cymantrenecarboxylate of heavier lanthanides (Ho, Er, Tm), Ln:Mn ratio of 1:2 is mixed complexes [20].binuclear In the casecomplexes of heavier 2-OAc)2(H2O)4]∙5H2O 2 -Obinuclear 2 -OAc) (H lanthanides (Ho, Er, Tm), complexes [Ln 2O) (μ 2-O 2CCym) 2-(η22-O 2CCym)2-(Figure (η 2 [Ln (µ -O CCym) -(η CCym) -(η ] · 5H O were obtained 2), lanthanides 2-(η -O2CCym)2-(η -OAc)2(H2while O)4]∙5H1D 2O 2 2 2 (Ho, Er, 2 Tm), binuclear 2 2 complexes2 [Ln22(μ24-O2CCym) 2 were obtained (Figure 2), while 1D polymers [Ln(O 2CCym) 2-(OAc)(A) xO; ] n∙mSolv (x = 1, 2; A MeOH, polymers [Ln(O CCym) -(OAc)(A) ] · mSolv (x = 1, 2; A = MeOH, H Solv = i-PrOH, THF, H2 O) n were obtained (Figure 2),2 while 1D xpolymers [Ln(O2CCym)2-(OAc)(A)2x]n∙mSolv (x = 1, 2; A == MeOH, 2 H22O; O; obtained Solv == i-PrOH, i-PrOH, THF, H O) were obtained in the the cases cases of Ln Ln == Nd, Nd, Gd, Gd, Dy Dy (Figure (Figure 3) 3) [20]. [20]. were in the THF, cases H of22O) Ln were = Nd,obtained Gd, Dy (Figure 3) [20]. H Solv in of

Figure 2. Molecular structure structure of of [Ln [Ln22(μ (μ22–O –O22CCym) CCym)44(OAc) (OAc)22(H (H22O) O)44]∙5H ]∙5H22O O (Ln (Ln == Ho, Ho, Er, Er, Tm). Tm). Reproduced Reproduced Figure Figure 2.2.Molecular Molecular structure of [Ln 2 (µ2 -O2 CCym)4 (OAc)2 (H2 O)4 ]·5H2 O (Ln = Ho, Er, Tm). from the work [20] with the change in appearance. from the work [20]the with the [20] change inthe appearance. Reproduced from work with change in appearance.

All of of the the polymers polymers include include aa common common ladder ladder structure structure {Ln(OAc)} {Ln(OAc)}nn formed formed by by tetradentate tetradentate All 3+ All of the polymers include a common ladder structure {Ln(OAc)} formed by tetradentate acetate acetate ligands ligands and and Ln Ln3+ ions. ions. Cymantrenecarboxylate Cymantrenecarboxylate anions anions form formnthe the periphery periphery of of the the polymer polymer acetate 3+ ligands and Lntheyions. anions form periphery of theThe polymer chain, chain, where where play Cymantrenecarboxylate the role role of of monodentate, monodentate, chelate orthe bridging ligands. diversity of chain, they play the chelate or bridging ligands. The diversity of where they play the roleofofthe monodentate, chelate or bridging ligands. Thethe diversity ofofcoordinating coordinating functions cymantrenecarboxylate residues determines variety the polymer coordinating functions of the cymantrenecarboxylate residues determines the variety of the polymer functions structures.of the cymantrenecarboxylate residues determines the variety of the polymer structures. structures.

Figure 3. 3. Molecular Molecular structure of [Ln(O [Ln(O22CCym) CCym)2(OAc)(A) ∙mSolv (Ln Nd, Gd, Dy; 1, 2; Molecular structure structure of (OAc)(A)xx]x]nn]∙mSolv (Ln===Nd, Nd, Gd, Gd, Dy; Dy; xxx === 1, 1, 2; 2; Figure 3. [Ln(O n ·mSolv(Ln 2 CCym)22(OAc)(A) A = MeOH, H 2O; Solv = i-PrOH, THF, H2O). Reproduced from the work [20] with the change A == MeOH, MeOH, HH22O; O; Solv Solv == i-PrOH, i-PrOH, THF, THF, H H22O). Reproduced from the work [20] with the change in appearance. appearance. in

The 1D-polymeric 1D-polymeric complexes complexes [Ln(η [Ln(η22-O -O22CCym) CCym)22(μ (μ22-O -O22CCym) CCym)44Ln(RОH) Ln(RОH)44]]nn∙mSolv ∙mSolv (Ln (Ln == Nd, Nd, Gd, Gd, The The 1D-polymeric complexes [Ln(η2 -O 2 CCym)2 (µ2 -O2 CCym)4 Ln(ROH)4 ]n ·mSolv (Ln = Nd, Gd, 5 Dy, Ho, Ho, Er; Er; R R == H, H, Me; Me; Cym Cym == (η (η5 -C55H H4)Mn(CO)33;; Solv Solv (solvent molecule)) molecule)) that we we obtained appeared appeared Dy, Dy, Ho, Er; R = H, Me; Cym = (η5-C -C5 H44)Mn(CO) )Mn(CO)3 ; Solv(solvent (solvent molecule)) that that we obtained obtained appeared to be rather interesting. The polymeric chains of these compounds contain two types of alternating to be rather rather interesting. interesting. The chains these compounds compounds contain contain two two types types of of alternating alternating to be The polymeric polymeric chains of of these 3+ ions that coordinate the water/methanol molecules and the oxygen coordination centers, namely, Ln 3+ 3+ ions coordination thatthat coordinate the water/methanol molecules and theand oxygen coordination centers, centers,namely, namely,LnLnions coordinate the water/methanol molecules the 3+ ions that coordinate the oxygen atoms of bridging and atoms of of bridging bridging carboxylate carboxylate anions anions and and Ln Ln3+ 3+ atoms ions that coordinate the oxygen atoms of bridging and oxygen atoms of bridging carboxylate anions and Ln ions that coordinate the oxygen atoms of chelate carboxylate carboxylate anions; anions; in in both both cases, cases, the the coordination coordination number number (CN) (CN) of of Ln Ln equals equals eight eight (Figure (Figure 4) 4) chelate [21]. [21].


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bridging and chelate carboxylate anions; in both cases, the coordination number (CN) of Ln equals eight (Figure 4)2016, [21]. Magnetochemistry 2, 38 4 of 15 Magnetochemistry 2016, 2, 38

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2-O2CCym)2(μ-O2CCym)4Ln(H2О)4]n. Reproduced from the Figure 4. 4. Molecular Molecularstructure structureofof[Ln(η [Ln(η 2 -O Figure 2 CCym) 2 (µ-O2 CCym)4 Ln(H2 O)4 ]n . Reproduced from the Figure 4. Molecular structure of [Ln(η2-O 2CCym)2(μ-O2CCym)4Ln(H2О)4]n. Reproduced from the work [21] with the change in appearance. work [21] with the change in appearance. work [21] with the change in appearance.

To synthesize cymantrenecarboxylates with the ratio Ln:Mn = 1:1, we suggested an original To synthesize cymantrenecarboxylates with the ratio Ln:Mn = 1:1, we suggested an original synthesize technique with the cymantrenecarboxylates use of hydrated lanthanide acetylacetonates as the starting reagents [22]. 1Dtechnique with with the theuse useofofhydrated hydratedlanthanide lanthanide acetylacetonates as the starting reagents acetylacetonates as the starting reagents [22]. [22]. 1Dpolymeric complexes [Ln(O 2CCym)(acac)2(H2O)]n (Ln = Eu, Gd, Tb, Dy, Ho, Er) were obtained. The 1D-polymeric complexes [Ln(O O)]n= (Ln =Gd, Eu,Tb, Gd,Dy, Tb,Ho, Dy, Er) Ho,were Er) were obtained. polymeric complexes [Ln(O 2CCym)(acac) 2(H2O)] Eu, obtained. The 2 CCym)(acac) 2 (Hn2(Ln structure of the complexes is formed of [Ln(acac)2(H2O)] moieties, in which the lanthanide ion is The structure of the complexes is formed of [Ln(acac) moieties, in which lanthanide structure of two the complexes is formed of bridging [Ln(acac) 2(H22(H O)]2 O)] moieties, in which thethe lanthanide ionion is chelated by acac ligands, while the cymantrenecarboxylate anions bind the adjacent is chelated by twoacac acacligands, ligands,while whilethe thebridging bridging cymantrenecarboxylateanions anions bind the adjacent chelated [Ln(acac)2by (H2two O)] moieties into an infinite chain. Thecymantrenecarboxylate coordination number of Ln3+3+isbind seven, which is a [Ln(acac)22(H (H22O)] O)]moieties moietiesinto intoan aninfinite infinitechain. chain.The Thecoordination coordinationnumber numberofofLn Ln3+ isisseven, seven,which whichisisa comparatively small value for lanthanide complexes (Figure 5). acomparatively comparativelysmall smallvalue valuefor forlanthanide lanthanidecomplexes complexes(Figure (Figure5).5).

Figure 5. Molecular structure of [Ln(O2CCym)(acac)2(H2O)]n (Ln = Eu–Er). Reproduced from the Figure 5. 5. Molecular structure structure of of [Ln(O [Ln(O2CCym)(acac) CCym)(acac)2(H 2O)]n (Ln = Eu–Er). Reproduced from the Figure work [22] Molecular with the change in appearance. 2 2 (H2 O)]n (Ln = Eu–Er). Reproduced from the work [22] with the change in appearance. work [22] with the change in appearance.

Moreover, new REE ferrocenecarboxylates [Ln2(μ-О,η2-OOCFc)2(μ2-О,О′-OOCFc)2(η22-OOCFc)2(μ2-О,О′-OOCFc)2(η2Moreover, new REE ferrocenecarboxylates [Ln2 2(μ-О,η 2 NO3)Moreover, 2(DMSO)4] (Ln = Gd, Y) and [Gd2(μ-О,η2-OOCFc) 2(η2-OOCFc) 4(DMSO) 2(H20O)2]∙2DMSO∙2CH 2Cl2 new REETb, ferrocenecarboxylates [Ln2 (µ-O,η -OOCFc) 2 (µ2 -O,O -OOCFc)2 (η -NO3 )2 2 2 NO 3)2(DMSO)4] (Ln = Gd, Tb, Y) and [Gd2(μ-О,η -OOCFc)2(η -OOCFc)4(DMSO)2(H2O)2]∙2DMSO∙2CH2Cl2 were obtained and characterized [23]. 2 Two new 2compounds were obtained in this study: (DMSO) 4 ] (Ln = Gd, Tb, Y) and [Gd2 (µ-O,η -OOCFc)2 (η -OOCFc)4 (DMSO)2 (H2 O)2 ]·2DMSO·2CH2 Cl2 were obtained and characterized [23].is isostructural Two new compounds obtained in this [Dy 2 (O 2 CFc) 4 (NO 3)2(DMSO) 4] (3), which with [Ln2(O2were CFc)4(NO 3)2(DMSO) ] (Lnstudy: = Gd, were obtained and characterized [23]. Two new compounds were obtained in 4this study: [Dy 2(O2CFc)4(NO3)2(DMSO)4] (3), which is isostructural with [Ln2(O2CFc)4(NO3)2(DMSO)4] (Ln = Gd, Tb, 2Y) and [Dy2(O2CFc)6(DMSO)2(H2O)2]∙2DMSO∙3MePh (4). [Dy (O[23], 2 CFc)4 (NO3 )2 (DMSO)4 ] (3), which is isostructural with [Ln2 (O2 CFc)4 (NO3 )2 (DMSO)4 ] (Ln = Gd, Tb, Y) [23], and [Dy2(O2CFc)6(DMSO)2(H2O)2]∙2DMSO∙3MePh (4). A number of 2 (O hitherto unknown ferrocenoylacetonate complexes of rare earth elements, Tb, Y) [23], and [Dy 2 CFc)6 (DMSO)2 (H2 O)2 ]·2DMSO·3MePh (4). A number of 6H hitherto unknown ferrocenoylacetonate complexes of rare earth elements, [Ln(fca) 3 (bpy)]∙MeC 5 (Ln = Pr, Eu, Gd, ferrocenoylacetonate Tb, Dy, Ho (fca = Fс(CO)CH(CO)Me; 2,2′-bipyridyl)) A number of hitherto unknown complexes of bpy rare =earth elements, [Ln(fca) 3(bpy)]∙MeC6H5 (Ln = Pr, Eu, Gd, Tb, Dy, Ho (fca = Fс(CO)CH(CO)Me; bpy = 2,2′-bipyridyl)) 0 -bipyridyl)) (Figure 36) [24] ·and 2(NO 3)(bpy)]∙nMeC 6HHo 5 (Ln = Sm, Eu, Dy, Er, Yb), were synthesized and [Ln(fca) (bpy)] MeC[Ln(fca) H (Ln = Pr, Eu, Gd, Tb, Dy, (fca = Fc(CO)CH(CO)Me; bpy = 2,2 6 5 (Figure 6) [24]by and [Ln(fca) 2(NO3)(bpy)]∙nMeC6H5 (Ln = Sm, Eu, Dy, Er, Yb), were synthesized and characterized X-ray single crystal analysis [25]. (Figure 6) [24] and [Ln(fca)2 (NO3 )(bpy)]·nMeC6 H5 (Ln = Sm, Eu, Dy, Er, Yb), were synthesized and characterized by X-ray single crystal analysis [25]. Thus, weby proposed methods foranalysis the synthesis characterized X-ray single crystal [25]. of new compounds, determined their molecular Thus, we proposed methodstheir for the synthesis of new compounds, determined their molecular and Thus, crystalwe structures, thermal behavior, well as luminescent properties for Eu proposedstudied methods for the synthesis of newascompounds, determined their molecular and crystal structures, studied their thermal behavior, as well as luminescent properties for Eu derivatives [15–25], but a detailed study of the magnetic behavior of some of the complexes was and crystal structures, studied their thermal behavior, as well as luminescent properties for not Eu derivatives [15–25], but a detailed study of the magnetic behavior of some of the complexes was not carried out. [15–25], but a detailed study of the magnetic behavior of some of the complexes was not derivatives carried out. Theout. diamagnetism of cymantrene and ferrocene moieties distinguishes lanthanide cymantrenecarried The diamagnetism of cymantrene and ferrocene moieties distinguishes lanthanide cymantreneand ferrocene-carboxylates from all ofand theferrocene other Fe-Ln and distinguishes Mn-Ln heterometallic The diamagnetism of cymantrene moieties lanthanidecompounds cymantrene-since and and ferrocene-carboxylates from all of the other Fe-Ln and Mn-Ln heterometallic compounds since 3+ their magnetism is caused bythe theother contribution ofMn-Ln Ln ions. The dc magnetic susceptibility for ferrocene-carboxylates fromonly all of Fe-Ln and heterometallic compounds since their their magnetism is caused by in thethe contribution ofrange Ln3+ ions. The K dcinmagnetic susceptibility for most of the complexes was only studied temperature of 2–300 an applied magnetic field most of the complexes was studied in the temperature range of 2–300 K in an applied magnetic field of 5000 Oe. It was shown that their magnetic behavior was determined by the lanthanide ions, and of Oe. K) It was shown that theircompounds magnetic behavior was determined lanthanide ions,[26]. and the5000 χT (300 values for all of the agreed satisfactorily with by thethe theoretical values the χT (300 K) values for all of the compounds agreed satisfactorily with the theoretical values [26].


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magnetism is caused only by the contribution of Ln3+ ions. The dc magnetic susceptibility for most of the complexes was studied in the temperature range of 2–300 K in an applied magnetic field of 5000 Oe. It was shown that their magnetic behavior was determined by the lanthanide ions, and the Magnetochemistry 2016,for 2, 38 χT (300 K) values all of the compounds agreed satisfactorily with the theoretical values [26].5 of 15

Figure 6. Molecular Molecularstructure structureofof[Ln(fca) [Ln(fca) = Pr, below, 3 (bpy)] Figure 6. 3(bpy)] (Ln(Ln = Pr, Eu,Eu, Gd,Gd, Tb, Tb, Dy,Dy, Ho);Ho); herehere and and below, the the ferrocene moieties are simplified for clarity. Reproduced from the work [24] with the change ferrocene moieties are simplified for clarity. Reproduced from the work [24] with the change in in appearance. appearance. 3+ are of particular interest Among compounds of light lanthanides lanthanides (Ce-Gd), complexes of Gd Gd3+ structure of this ion: ion: it hasitthe maximum possiblepossible number number of unpaired electrons due to tothe theelectronic electronic structure of this has the maximum of unpaired (S = 7/2) among 4f-elements. Moreover, itMoreover, is an isotropic ionisotropic with zero from spin-orbital electrons (S = 7/2) among 4f-elements. it is an ioncontribution with zero contribution from 3+ coupling, which considerably facilitates the mathematical description of magnetism for spin-orbital coupling, which considerably facilitates the mathematical description of magnetismGd for 3+ 3+ 3+ complexes. The experimental χmT(Т) dependences forfor binuclear Gd complexes. The experimental χm T(T) dependences binuclearand andpolynuclear polynuclear Gd complexes with thethe [Gd 2 O 2 ] core are usually interpreted using equations derived from the [Gd2 O2 ] core are usually interpreted using equations derived from the Heisenberg–Dirac–Van Heisenberg–Dirac–Van Hamiltonian = −JSGdconstant) SGd′ (J: exchange coupling constant) with 0 (J: exchangeH Vleck Hamiltonian H = −Vleck JSGd SGd coupling with isotropic spin and the quantum isotropicSspin and the quantum number S Gd = SGd′ = 7/2 [27,28]. 0 number = S = 7/2 [27,28]. Gd Gd 3+3+ For binuclear complexes both ferromagnetic and and antiferromagnetic interactions with small binuclearGd Gd complexes both ferromagnetic antiferromagnetic interactions with −1 − 1 absolute values values J have Jbeen (below (below 0.2 cm 0.2 ). The nature ofnature the Gd…Gd small absolute haveobserved been observed cm ferromagnetic ). The ferromagnetic of the interaction was supported by magnetization measurements in the 0–5in T the range K [29]. Gd. . . Gd interaction was supported by magnetization measurements 0–5atT 2range at Relative 2 K [29]. expanded uncertainties U r (J) are not presented in the literature (see the references in the work Relative expanded uncertainties Ur (J) are not presented in the literature (see the references in [30] the 2/Σ[(χ2m)obs]2), which 2 and in Table The fitting leads leads to Jex,tog Jand (R = Σ[(χ m ) obs − (χ m ) calc ] work [30] and 1). in Table 1). The procedure fitting procedure , g and (R = Σ[(χ ) − (χ ) ] /Σ[(χ ) ex m obs m calc m obs ] ), allows allows one to one evaluate Ur(J). UUr(J) must not less than 10% (±0.01). which to evaluate Ur (J)bemust be not less than 10% (±0.01). r (J). magnetostructural correlation for gadolinium complexes with The problem problem ofofestablishing establishingthethe magnetostructural correlation for gadolinium complexes the [Gd 2] core has been considered earlier [31–33]. The experimental data that we obtained for with the2O[Gd O ] core has been considered earlier [31–33]. The experimental data that we 2 2 [Gd 2 (O 2 CCym) 6 (THF) 4 ]∙THF [15] and [Gd 2 (O 2 CCym) 6 (py) 4 ]∙2py [16] and the available sufficiently obtained for [Gd2 (O2 CCym)6 (THF)4 ]·THF [15] and [Gd2 (O2 CCym)6 (py)4 ]·2py [16] and the available abundant data for 34 data gadolinium complexes complexes with the [Gd 2O2the ] motive usallowed to suggest a sufficiently abundant for 34 gadolinium with [Gd2 Oallowed us to 2 ] motive correlation between the JGd-Gd′ value the Gd…Gd distance in the complexes [30]. The determined 0 suggest a correlation between the Jand value and the Gd. . . Gd distance in the complexes [30]. Gd-Gd empirical dependence wasdependence satisfactorily approximated a fourth degree with R2 = 0.854 The determined empirical was satisfactorilyby approximated by apolynomial fourth degree polynomial 3+ 2 3+ [30]. RIt was found thefound antiferromagnetic interaction interaction between the Gd ions weakens with an with = 0.854 [30].that It was that the antiferromagnetic between the Gd ions weakens increase in the distance; at D Gd…Gd′ above ~4.10 Å, it changes to ferromagnetic coupling that passes with an increase in the distance; at DGd. . . Gd0 above ~4.10 Å, it changes to ferromagnetic coupling through a maximum DGd…Gd′ ≈(at 4.25 Å). .and approaches zero at DGd…Gd′ > 4.50 Å (Figure 7). The that passes through a(at maximum DGd. Gd0 ≈ 4.25 Å) and approaches zero at DGd. . . Gd0 > 4.50 Å authors7).[34] note[34] that thewithin framework of the of [Gd 2O 2] core, exchange coupling is (Figure Thealso authors alsowithin note that the framework the [Gd exchange coupling 2 O2 ] core, ferromagnetic when the Gd…Gd distance is larger than ~4.0–4.1 Å, while the exchange coupling is is ferromagnetic when the Gd. . . Gd distance is larger than ~4.0–4.1 Å, while the exchange is smaller. smaller. antiferromagnetic when this parameter is validityofof correlation was confirmed by the data[Gd for2 Ofour [Gd2O2] synthesized complexes The validity thisthis correlation was confirmed by the data for four 2 ] complexes synthesized by us (marked with asterisks in Table 1 and by blue points in Figure 7) [30]. The plot of by us (marked with asterisks in Table 1 and by blue points in Figure 7) [30]. The plot of the dependence thesimilar dependence is similar to curve the Bethe–Slater curvewhich (Figure 7, insert) the which represents the magnitude is to the Bethe–Slater (Figure 7, insert) represents magnitude of direct exchange of direct exchange as a function of a/r ratio, where a is the distance between two nearby atoms, and r is the radius of the unfilled electron shell [35].


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as a function of a/r ratio, where a is the distance between two nearby atoms, and r is the radius of the unfilled electron Magnetochemistry 2016, 38[35]. of15 15 Magnetochemistry 2016, 2,2016, 38shell 6 of 15 66of Magnetochemistry 2,2,38

Figure Approximation ofthe thedependence dependence of Gd-Gd′ vs.Gd…Gd′ Gd…Gd′ distance for49 49 O222]]]complexes complexes 0 vs. 7.7.Approximation ofof JGd-Gd Gd. . . Gd0 distance distance complexes FigureFigure 7. Approximation of theof dependence of JGd-Gd′ vs. Gd…Gd′ distance for 49 for [Gd 2O[Gd 2[Gd ] complexes Approximation of the dependence JJGd-Gd′ [Gd 222O (o, values used for building of the plot in the work [30]; ●, values reported in the work [30], butnot not (o, values used reported the work [30], but (o, values used for building of the of plot the in work values reported in the in work [30], but not for building theinplot the [30]; work●,[30]; ●,, values usedbuilding forbuilding building ofcorrelation; the correlation; correlation; ●, newly-added newly-added data (Table 1)).relative The relative expanded for correlation; data (Table 1)).(Table The expanded uncertainties used used for of of thethe ●,, newly-added newly-added data (Table 1)). relative The expanded for building of the ●, data 1)). The relative expanded uncertainties areshown. shown. Insert: Bethe–Slater curve[35]. [35]. are shown. Insert: Bethe–Slater curve [35]. uncertainties are shown. Insert:Insert: Bethe–Slater curve curve [35]. uncertainties are Bethe–Slater

In the work work [30], the results results of the studies studies carried out before before the2013 year were 2013 were were summarized. summarized. In theIn work [30], the results of theof studies carried out before the year summarized. In the work [30], the results the studies carried out the year 2013 the [30], the of the carried out before the year 2013 were summarized. However, presently, this problem is still under research [34]. Therefore, we decided to supplement However, presently, this this problem is still under research [34]. Therefore, wewe decided to to supplement However, presently, thisproblem problem still under research [34]. Therefore, we decided to supplement However, presently, isisstill under research [34]. Therefore, decided supplement the the information information provided in our earlier earlier work [30] with bothliterature our literature anddata, literature data, which the information provided in our our earlier work [30] with both our and data, data, which is the provided in our work [30] both our and literature which isis information provided in earlier work [30] with bothwith our and which is presented in presented in this paper (Table 1 and red points in Figure 7). presented in thisin paper (Table 1 and in7). Figure 7). 7). presented this 1paper (Table 1red and red points in Figure this paper (Table and red points inpoints Figure Table TheGd. Gd…Gd′ distances and theexchange exchange coupling parameter Gd-Gd′ for O22]]complexes. complexes. TableTable 1. The1.1.1. Gd…Gd′ and the exchange coupling parameter JGd-Gd′J for [Gd 2O[Gd 2[Gd ] complexes. Table The Gd…Gd′ distances and the exchange coupling parameter JJGd-Gd′ for 22O The .distances . Gd0 distances and the coupling parameter Gd-Gd0 for [Gd2 O2 ] complexes. −1 −1,, cm −1 Compound DGd…Gd′ Å J,JGd-Gd′ Gd-Gd′ cm Ref. Compound DGd…Gd′ ,Gd…Gd′ Å J,,Gd-Gd′ cm Ref. Compound D Å Ref. −1 0 0 J , cm D , Å Gd. . . Gd [Gd (H L)242(piv) (piv)44]·2CHCl ]∙2CHCl 3.665 Gd-Gd −0.19[36] Reference [36] [Gd2(H 2L)222(H (piv) ]·2CHCl 3 3.665 3.665 −0.19 −0.19 [Gd 22L) 33 [36] [Gd (H L) (piv) ] · 2CHCl 3.665 − 0.19 [36] 2 2 2 4 3 [Gd 2 (valdien) 2 (NO ) 2 ] 3.811 −0.178 [37] [Gd2(valdien) 2(NO32)(NO 2] 3.811 3.811 −0.178−0.178[37] [37] [Gd2(valdien) 3)2] [Gd2 (valdien) (NO ) ] 3.811 − 0.178 [37] 1 2 3 2 [Gd (O22CMe) (H L1))22](ClO )22·2H ∙2H22O·2MeOH O∙2MeOH 3.920 3.920 3.920 −0.033−0.033 −0.033[34] [34] [34] [Gd2(O 2CMe) 4CMe) (H2L144)(H 2](ClO 4](ClO )2·2H424)O·2MeOH [Gd 22(O 22L 3.920 −0.033 [34] [Gd2 (O2 CMe)4 (H2 L1 )2 ](ClO4 )2 ·2H2 O·2MeOH [Gd(O 2 CCym) 2 (OAc)(H 2 O) 2 ] n ∙2nH 2 O 3.968 −0.038 [20] [Gd(O 2CCym) 2(OAc)(H 2O)2]n2·2nH O 2O 3.968 3.968 −0.038 [Gd(O 2CCym) 2(OAc)(H O)2]n2·2nH −0.038[20] [20] [Gd(O 3.968 −0.038 [20] 2 CCym)2 (OAc)(H2 O)2 ]n ·2nH2 O [Gd 2(O (O 2CCym) CCym) 4(NO (NO 3))22(DME) (DME) 2]] 3.970 −0,068 [19] [Gd 2 CCym) 4 (NO 3 ) 2 (DME) 2 ] 3.970 −0,068 [19] [Gd 2 2 4 3 2 3.970 −0,068 [19] [Gd2(O (O CCym) (NO ) (DME) 3.970 − 0,068 [19] 2 2 4 3 2 2 [Gd2(Piv) (Piv) (phen) 3.978 −0.020 [30] [Gd262(Piv) (phen) 3.978 −0.020 −0.020[30] [30] [30] [Gd (phen) 22]] ** 3.978 3.978 2[Gd 6(Piv) 66(phen) 22]] ** −0.020 [(CO ) {Ni(3-MeOsaltn)(MeOH)Gd(NO )} ] 3.989 − 0.012 [38] 3 2 3 2 [(CO 3 ) 2 {Ni(3-MeOsaltn)(MeOH)Gd(NO 3 )} 2 ] 3.989 −0.012 [38] [(CO3[(CO )2{Ni(3-MeOsaltn)(MeOH)Gd(NO 3)}2] 3)}2] 3.989 3.989 −0.012−0.012[38] [38] 3)2{Ni(3-MeOsaltn)(MeOH)Gd(NO [Gd2 (Piv)6 (bipy)2 ] * 4.014 −0.033 [30] [Gd262(Piv) (Piv) (bipy) 4.014 −0.033−0.033 −0.033[30] [30] [30] [Gd 2(Piv) (bipy) 2] * 4.014 4.014 [Gd 66(bipy) 22]] ** 2 4.050 0.028 [39] [(CO3 )2 {ZnL Gd(NO3 )}2 ] [(CO {ZnL22Gd(NO Gd(NO )}22]] 4.050 0.028 0.028[39] [39] [39] [(CO )(O 2{ZnL Gd(NO 3)}2] 33)} 4.050 4.050 33))222{ZnL 0.028 [Gd23[(CO 4.058 −0.050 [30] 2 CCym)6 (DMSO)4 ] * [Gd (O224CCym) CCym) 6(DMSO) (DMSO) 4.058 −0.050 −0.050[30] [30] [30] [Gd2(O (O (NO 4.067 −0.040 [23] [Gd 2CCym) 6(DMSO) 4] * 4 ]44]] ** 4.058 4.058 22(O −0.050 2[Gd 2 CFc) 3 )26(DMSO) [Gd (Piv) (bath) ] * 4.224 0.004 [30] [Gd CFc) (DMSO) 4.067 −0.040−0.040 −0.040[23] [23] [23] 2[Gd 6(O422(NO 2 34)4(NO [Gd2(O 2CFc) 2(NO (DMSO) 4] 4.067 4.067 22(O CFc) 33))22(DMSO) 44]] [Gd2 (O CFc) (DMSO) (H O) ] · 2DMSO · 2CH Cl 4.348 0.029 [23] 2 62(bath) 6 6(bath) 22] *2 2 2 2 [Gd (Piv) 4.224 0.004 0.004 0.004[30] [30] [30] [Gd2(Piv) 2] * 4.224 4.224 [Gd 2(Piv) 6(bath) 2] * [Gd2 (O2 CC6 H3 (NO2 )2 )6 (DMSO)4 ]·3MePh 4.380 0.003 [40] [Gd (O622(DMSO) CFc)66(DMSO) (DMSO) O)22]·2DMSO·2CH ]∙2DMSO∙2CH Cl24.348 2 4.348 0.029 0.029[23] [23] [23] [Gd 2CFc) 2(H2O) 2(H ]·2DMSO·2CH 2Cl2 22Cl [Gd 22(O CFc) 22(H 22O) 4.348 0.029 [Gd2(O 4.435 0.017 [40] 2 (O2 CC6 H3 (NO2 )2 )6 (DMSO)4 ]·3(Me2 N)C6 H5 [Gd (O H23)3(NO (DMSO) ]∙3MePh 4.380 0.003 0.003 0.003[40] [40] [40] [Gd 2(O 2CC 6H 3CC (NO 2(NO ) 6(DMSO) 4]·3MePh 4.380 [Gd 22(O 22CC 66H 22))22))66(DMSO) 44]·3MePh 4.380 * The complexes used for correlation test in the work [27]; H3 L = 2,2’-(2-hydroxy-3-methoxy-5[Gd (O H23)3(NO (DMSO) ]∙3(Me 2N)C N)C H 4.435 0.017[40] [40] [40] [Gd 2(O 2CC 6H 3CC (NO 2(NO )6(DMSO) 4Hpiv ]·3(Me 2pivalic N)C62H 5 0.017 0.017 [Gd 22(O 22CC 66H 22))22))66(DMSO) 4=4]·3(Me 66H 4.435 methylbenzylazanediyl)diethanol; acid; H5524.435 valdien = N1,N3-bis(3-methoxysalicylidene)

Compound

1

diethylenetriamine; H2 L for = bis(5-methylimidazol-4-yl-methylideneaminopropyl)methylamine; phen = 1,10The complexes complexes used correlation test in the work workH [27]; H 2,2’-(2-hydroxy-3-methoxy-5* The **complexes used for correlation test intest thein work [27]; 3L =H 2,2’-(2-hydroxy-3-methoxy-5The used for correlation the [27]; 33LL == 2,2’-(2-hydroxy-3-methoxy-5phenanthroline; 3-MeOsaltn = N,N 0 -bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; bipy = 2,2’methylbenzylazanediyl)diethanol; Hpiv pivalic acid; Hbath valdien N1,N3-bis(3methylbenzylazanediyl)diethanol; Hpiv Hpiv = pivalic acid; acid; H2valdien N1,N3-bis(3methylbenzylazanediyl)diethanol; == pivalic H 22valdien == N1,N3-bis(3bipyridyl; L2 = N,N 0 -bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; == bathophenanthroline. 1 1 1 2 L = bis(5-methylimidazol-4-ylmethoxysalicylidene)diethylenetriamine; H = methoxysalicylidene)diethylenetriamine; = bis(5-methylimidazol-4-ylbis(5-methylimidazol-4-ylmethoxysalicylidene)diethylenetriamine; H2L H2L methylideneaminopropyl)methylamine; phen = 1,10-phenanthroline; 1,10-phenanthroline; 3-MeOsaltn N,N′-bis(3methylideneaminopropyl)methylamine; phen = 1,10-phenanthroline; 3-MeOsaltn = N,N′-bis(3methylideneaminopropyl)methylamine; phen = 3-MeOsaltn == N,N′-bis(3Taking into account additional findings, together with the previously used data, allowed enhancing N,N′-bis(3-methoxy-2methoxy-2-oxybenzylidene)-1,3-propanediaminato; bipy 2,2’-bipyridyl; methoxy-2-oxybenzylidene)-1,3-propanediaminato; bipy =bipy 2,2’-bipyridyl; L2 = N,N′-bis(3-methoxy-2methoxy-2-oxybenzylidene)-1,3-propanediaminato; ==2,2’-bipyridyl; LL22==N,N′-bis(3-methoxy-22 the reliability of the correlation (R = 0.875). As can be seen from Figure 7, these data also confirm the oxybenzylidene)-1,3-propanediaminato; bath bathophenanthroline. oxybenzylidene)-1,3-propanediaminato; bath =bath bathophenanthroline. oxybenzylidene)-1,3-propanediaminato; ==bathophenanthroline.

validity of the correlation that we found. Taking into account account additional findings, together withpreviously the previously previously used data, allowed Taking into account additional findings, together with with the used used data, data, allowed Taking into additional findings, together the allowed 2 = 0.875). As can be seen from Figure 7, these data also 2 2 enhancing the reliability of the correlation (R enhancing the reliability of theofcorrelation (R = 0.875). As can seen FigureFigure 7, these data also enhancing the reliability the correlation (R = 0.875). Asbecan be from seen from 7, these data also confirm thevalidity validity of thecorrelation correlation that wefound. found. confirm the validity of theof correlation that we found. confirm the the that we should benoted noted thatsmall smallnegative negative values areobserved observed in theof area ofGd…Gd longGd…Gd Gd…Gd distances It should be noted that small negative J values are observed in thein area long distances ItItshould be that JJvalues are the area of long distances (Figure 7). This may be due to the influence of factors other than Gd…Gd distance, which we have have (Figure 7). This due thetoinfluence of factors other other than Gd…Gd distance, whichwhich we have (Figure 7). may This be may betodue the influence of factors than Gd…Gd distance, we


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It should be noted that small negative J values are observed in the area of long Gd. . . Gd distances (Figure 7). However, This may be to theexpanded influenceuncertainty of factors other thanthat Gd.small . . Gd distance, neglected. thedue relative suggests positive Jwhich valueswe arehave also neglected. the relative expanded uncertainty smalldistances positive are J values also possible in However, this region. The J values corresponding to thesuggests longest that Gd…Gd very are close to possible in this region. The J values corresponding to the longest Gd. . . Gd distances are very close to zero, as expected. zero,Furthermore, as expected. the following dysprosium compounds were studied: [Dy2(O2CCym)6(DMSO)4] (1), Furthermore, the following were 2 (O2 CCym) 6 (DMSO) 4] [Dy2(O 2CCym)4(NО 3)2(DMSO) 4] dysprosium (2),compounds [Dy 2(O2studied: CFc)4(NO[Dy 3)2(DMSO) 4] (3), 2 (1), [Dy (O CCym) (NO ) (DMSO) ] (2), [Dy (O CFc) (NO ) (DMSO) ] (3), [Dy (O CFc) (DMSO) 2 6(DMSO) 4 2(H32O) 2 2]∙2DMSO∙3MePh 4 2 (4), 2 4 3 22CCym)2(μ-O 4 2 4Dy(H 2 [Dy2(O22CFc) [Dy(η -O 2CCym) 26О)4]n (5),2 2 (H ]·2DMSO·3MePh (4), [Dy(η 2 O)2CCym)(acac) 2 CCym) 2 (µ-O2 CCym) 4 Dy(H2 O)4 ]n (5), [Dy(O2 CCym)(acac)2 [Dy(O 2(H2O)] n (6) and -O [Dy(fca) 3(bpy)]∙MeC 6H5 (7). (H2 O)] [Dy(fca)3 (bpy)]·MeC6 H51 (7). n (6) andcymantrenecarboxylates Binuclear were 2 were prepared and structurally characterized earlier Binuclear cymantrenecarboxylates were were prepared [18]; dysprosium ferrocenecarboxylates 3 1and 4 are2 newly obtained. and structurally characterized earlier [18]; dysprosium ferrocenecarboxylates 3 and 4 are newly obtained. The cymantrenecarboxylate anion is the core-forming ligand in Compounds 1 and 2, whereas The cymantrenecarboxylate anion is the core-forming ligand in Compounds 1 3and the the ferrocenecarboxylate anion plays this role in Structures 3 and 4. Structures 1, 2, and2,4whereas are formed ferrocenecarboxylate anion plays this role in Structures 3 and 4. Structures 1, 2, 3 and 4 are formed by by centrosymmetric dimers (Figure 8). centrosymmetric dimers (Figureof8).Dy atoms in Structure 1 is nine. The coordination polyhedron is The coordination number The coordination number of Dy prism. atoms The in Structure is the nine. The of coordination is best described as a three-cap trigonal structure1 of dimer Compoundpolyhedron 2 is similar to 2 beststructure describedofas a three-cap1 trigonal The structure of ligands, the dimer Compound 2 is similar the Compound with the prism. replacement of chelate i.e.,ofthe {η -О2СCym} ligand, 2to the structure of Compound 1 with thefrom replacement of chelate i.e., the {η2 -O{μ-О,η 2 CCym} for {η2-NО 3}. Furthermore, on transition Compounds 1 to 2,ligands, the chelate-bridging 2 -NO }. Furthermore, on transition from Compounds 1 to 2, the chelate-bridging ligand, for {η 3 ligands turn in such a way that they become purely bridging {μ2O2CCym} cymantrenecarboxylate 2 {µ-O,η cymantrenecarboxylate turn such way that become bridging О,О′-O-O 2CCym} ligands, which results in aligands decrease ininthe CNa from ninethey (1) down topurely eight (2) and a 2 CCym} 0 -O CCym} ligands, which results in a decrease in the CN from nine (1) down to eight (2) and {µ -O,O 2 2 increase in the Dy…Dy′ distance from 4.0513(6)–4.1775(4) Å, respectively. In Structure considerable 0 distance from 4.0513(6)–4.1775(4) Å, respectively. In Structure 3, a considerable increase in the by Dy.two . . Dybridging 3, two Dy atoms are bound and two chelate-bridging O2CFc ligands, similarly to two Dy atoms are bound of byDy two bridging and two chelate-bridging ligands, similarly to Structure 1. Coordination is also complemented by a NO3− chelateOion and two oxygen atoms 2 CFc − chelate ion and two oxygen atoms of Structure 1. Coordination of Dy is also complemented by a NO of DMSO molecules (CN = 9); the Dy…Dy′ distance is 4.042 Å. In 3 Structure 4, two Dy atoms are bound DMSO (CN =ligands; 9); the Dy. . . Dy0 distance is 4.042 Å. In Structure two atoms areligands bound coordination of Dy is complemented by 4, two ODy 2CFc chelate by two molecules O2CFc bridging by two ligands; coordination of Dy is water complemented O2 CFcdistance chelate ligands and twoOoxygen atoms from molecules of DMSO and (CN = 8); by thetwo Dy…Dy′ is 4.376 2 CFc bridging and two oxygen atoms from molecules of DMSO and water (CN = 8); the Dy. . . Dy’ distance is 4.376 Å. Å.

Figure 8. Molecular Figure 8. Molecular structures structures of of Compounds Compounds 11 [18] [18] (reproduced (reproduced with with the the change change in in appearance), appearance), 22 [18] (reproduced with the change in appearance), 3 and 4. [18] (reproduced with the change in appearance), 3 and 4.

DC magnetic measurements were carried out for Complexes 2, 3 and 4 for the first time. The χmT DC magnetic measurements were carried out for Complexes 2, 3 and 4 for the first time. The χm T 3+ ions (6H15/2 , values of complexes at 300 K (Table 2) correspond to two magnetically-isolated free Dy 3+ values of complexes at 300 K (Table 2) correspond to two magnetically-isolated free Dy ions (6 H15/2 , S = 5/2, L = 5, g = 4/3). S = 5/2, L = 5, g = 4/3).


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Table 2. Table 2. Magnetic Magnetic characteristics characteristics of of Complexes Complexes 1–4. 1–4. χmT (300χK)T (300 K) χm3T·mol (theor) −1·K [26] m χmT (theor) cm −1 3 cm3·mol cm·K ·mol−1 ·K cm3 ·mol−1 ·K [26] [Dy2(O2CCym)6(DMSO)4] (1) 28.71 [18] [Dy2 (O ] (1) 2 CCym) 6 (DMSO) [Dy2(O2CCym) 4(NО 3)2(DMSO) 4] (2) 4 28.67 28.71 [18] 28.34 (O2 CCym) 28.67 4 (NO3 )42](DMSO) 4 ] (2) 28.37 [Dy[Dy 2(O22CFc) 4(NO3)2(DMSO) (3) 28.34 [Dy (O CFc) (NO ) (DMSO) ] (3) 28.37 2 62(DMSO) 4 2(H23O) 2 2] (4) 4 [Dy2(O2CFc) 28.77 Complex Complex

[Dy2 (O2 CFc)6 (DMSO)2 (H2 O)2 ] (4)

28.77

T (2 3·mol−1·K χmTχ(2mK) cmK) cm3 ·mol−1 ·K 20.10

20.10 18.31 18.31 15.21 15.21 14.88 14.88

As the temperature decreases to 100 K, the χmT values of dysprosium complexes weakly depend As the temperature decreases to 100 K, the χm T values of dysprosium complexes weakly depend on temperature, but on further temperature lowering, the absolute values decrease considerably. The on temperature, further lowering, absolute values decrease considerably. minimum values but are on attained at temperature 2 K (Figure S1, Table 2).the This behavior is caused by the splitting of The minimum are attained at 2ligand K (Figure Tableby 2).the This behavior is caused splitting of mJ levels in thevalues zero field due to the fieldS1, effect, Zeeman effect under by thethe external field m the zero field due to thecoupling ligand field effect, bylanthanide the Zeeman effect under the external field and/or byinweak antiferromagnetic between the ions. J levels and/or by weak antiferromagnetic coupling between the lanthanide ions. To explore the presence of the slow relaxation of magnetization in the case of Dy complexes, To explore the presence of magnetic the slow relaxation of magnetization case of Dy at complexes, dynamic measurements of ac susceptibility as a functioninofthe temperature variable dynamic measurements of ac for magnetic susceptibility as a samples function ofof some temperature at variable frequencies were performed polycrystalline powder complexes in the frequencies were performed for polycrystalline powder samples of some complexes in the temperature temperature range of 2–12 K. Such measurements for Complexes 2–4 were also carried out for the range of 2–12 K. Such measurements for Complexes 2–4 were also carried out for the first time. first time. For binuclear CCym)66(DMSO) (DMSO)4]4 ] (1), (1), we we have have measured measured the the ac magnetic binuclear complex complex [Dy [Dy22(O 2CCym) susceptibility in the dc field with the intensities H = 0 and 5 kOe only for three frequencies earlier [18]. susceptibility in the dc field with the intensities H = 0 and 5 kOe only for three frequencies earlier In the external field, thethe temperature dependences ofof the [18]. Inzero the zero external field, temperature dependences theimaginary imaginarycomponent componentcontain contain the 00 , but no distinctly detected maximum was frequency-dependent signal and a noticeable increase in χ frequency-dependent signal and a noticeable increase in χ″, 00 (T) dependences is observed. As As the field intensity increases to H = 5 kOe, the maximum in the χχ″ observed (100 Hz, 1 kHz and 10 10 kHz)) at observed in in the the range range4.5–5 4.5–5KKatatall allfrequencies frequencies(only (onlythree threefrequencies frequencies (100 Hz, 1 kHz and kHz)) which the measurements were carried out [18]. at which the measurements were carried out [18]. In this range of of 2–52–5 K in 1000 andand 20002000 Oe this work, work, Complex Complex11was wasstudied studiedininthe thetemperature temperature range K zero, in zero, 1000 00 external fields for for a wide range of of frequencies (10–10,000 Hz). Oe external fields a wide range frequencies (10–10,000 Hz).AAfrequency-dependent frequency-dependent signal signal χχ″ 00 (ν) plot does not is observed in this temperature range, but the position of the maximum maximum in the the χχ″(ν) change with the temperature variation (Figure S2), which may be due to the quantum quantum tunneling effect. On Onapplication applicationofofthe themagnetic magneticfield fieldwith withupup to an H = 2000 Oe strength, maximum in to an H = 2000 Oe strength, the the maximum in the 00 the χ (T) is observed themeasurement measurementtemperatures, temperatures,but butno noshift shiftof of the the maximum maximum is χ″ (T) plotplot is observed at at allall of of the observed behavior of the χ00 (ν) plot plot indicates that slow relaxation is present, observed (Figure (FigureS3). S3).This This behavior of the χ″(ν) indicates that magnetic slow magnetic relaxation is but the effect of quantum tunneling decreases insignificantly upon the application of an external present, but the effect of quantum tunneling decreases insignificantly upon the application of an magnetic field. external magnetic field. Furthermore, we (DMSO)44]] (2). (2). we carried carried out out studies studiesfor forbinuclear binuclearcomplex complex[Dy [Dy2 (O 2(O CCym)44(NO (NО33)2(DMSO) 22CCym) 00 For Complex 2, non-zero χχ″ values are observed even in the zero field (Figure (Figure 9). 9).

(a)

(b)

Figure 9.9.Frequency Frequency dependence of in-phase the in-phase (χ′, out-of-phase a) and out-of-phase (χ″, b)susceptibility, parts of ac Figure dependence of the (χ0 , a) and (χ00 , b) parts of ac susceptibility, between 2 and 6 K, for 2 in the zero dc field. Solid lines are visual guides. between 2 and 6 K, for 2 in the zero dc field. Solid lines are visual guides.

The τ vs. T−1 plot for Complex 2 is presented in Figure S4 and Figure 10 (empty squares). Fitting the τ(T−1) plot to the Arrhenius equation in the temperature range of 2–6 K allowed us to determine


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The τ vs. 2016, T −1 plot for Complex 2 Magnetochemistry Magnetochemistry2016, 2016,2,2,2,38 38 Magnetochemistry 38 − Fitting the τ(T 1 ) plot to the Arrhenius

is presented in Figure S4 and Figure 10 (empty squares). 999of of15 15 of 15 equation in the temperature range of 2–6 K allowed us to determine the potential barrier of magnetization reversal, 53 K, and thepre-exponential pre-exponentialfactor, factor, the barrier reversal, ΔE/k B∆E/k the B thepotential potential barrierof ofmagnetization magnetization reversal, ΔE/k 53=K, K,and and the pre-exponential factor, the potential barrier of magnetization reversal, ΔE/k BB===53 53 K, and the pre-exponential factor, −−99 s. −9 ττ00τ0=0===3.2∙10 3.2 · 10 −9 s. 3.2·10 s.s. 3.2·10 The dynamics ofof 222was also studied under anan applied dcdc magnetic field in in order to magnetization dynamics also studied under applied field Themagnetization magnetization dynamics of 2was was also studied under an applied dcmagnetic magnetic field inorder order The magnetization dynamics of was also studied under an applied dc magnetic field in order minimize thethe probability ofof quantum tunneling (Figure S5). ItItIt was found that the external to probability tunneling (Figure S5). found that the external tominimize minimize the probability ofquantum quantum tunneling (Figure S5). Itwas was found that the externalmagnetic magnetic to minimize the probability of quantum tunneling (Figure S5). was found that the external magnetic field did not affect considerably the relaxation processes in Complex 2 (Figure 10). not affect considerably the relaxation processes in Complex 2 (Figure 10). fielddid didnot notaffect affectconsiderably considerablythe therelaxation relaxationprocesses processesin inComplex Complex22(Figure (Figure10). 10). field

Figure 10. vs. TT− 2(O 2CCym) 4(NО 3) 4] in aaazero ))dc Figure10. 10.ττττvs. vs.T T−11−1plot plotfor for[Dy [Dy 2(O (O 2CCym) CCym) 4(NO (NО )2(DMSO) 22(DMSO) ]](2) (2) in zero (□) and1000 1000Oe Oe((■(■■ )dc dcfield. field. Figure 10. vs. plot for [Dy 22CCym) 44(NО 33 )23(DMSO) 4]44(2) in (□) and 1000 Oe dc field. Figure plot (DMSO) (2) in azero zero(□) ( )and and 1000 Oe field. 22(O −9−9 − 9 −9 The solid red line is the best fit to the Arrhenius law (τ 0 = 3.2 × 10 s, ΔE/k B = 53 K) (this study). The red line isisis the best fitfit toto the Arrhenius law (τ(τ 3.2 ∆E/k =5353 (this study). Thesolid solid red line the best fit to the Arrhenius law 0== 3.2× 10 s,s,s,ΔE/k ΔE/k K)K) (this study). The solid red line the best the Arrhenius law 3.2 ××10 BB= K) (this study). 0(τ0= B=53 −1

No non-zero out-of-phase component of ac magnetic susceptibility was found for Complex Nonon-zero non-zeroout-of-phase out-of-phasecomponent componentof ofac acmagnetic magneticsusceptibility susceptibilityχχ″ wasfound foundfor forComplex Complex3333 No non-zero out-of-phase component of ac magnetic susceptibility χ″ was found for Complex 00χ″was No atattemperatures above 2 KKin frequency range of Hz, in field temperatures above inthe the frequency range of10–10,000 10–10,000 Hz,both both inthe thezero zeromagnetic magnetic field temperatures above the frequency range of 10–10,000 both in the zero magnetic atat temperatures above 2 2K2K in in the frequency range of 10–10,000 Hz,Hz, both in the zero magnetic field field and and under an external magnetic field of 5000 Oe (Figures S6–S8). andunder under anexternal external magnetic field ofOe 5000 Oe(Figures (Figures S6–S8). and an magnetic field of 5000 Oe S6–S8). under an external magnetic field of 5000 (Figures S6–S8). In the case of the new complex [Dy 22(O 22CFc) 66(DMSO) 22(H 22O) 22]] (4), In the case of the new complex [Dy 2(O (O 2CFc) 6(DMSO) (DMSO) 2(H (H 2O) O) 2] (4),aaafrequency-dependent frequency-dependentsignal signal In the case of the new complex [Dy CFc) (4), frequency-dependent signal In the case of the new complex [Dy2 (O2 CFc)6 (DMSO)2 (H 2 O)2 ] (4), a frequency-dependent signal χ″ is almost not observed in the zero external field at 2 K. On increasing the dc field strength to = χ″is almostnot notobserved observedin inthe the zero external field atat222K. K.K. On increasing the dcdc field strength toHHH isisalmost almost On increasing the dc field strength to 00 χχ″ not observed in thezero zeroexternal externalfield fieldat On increasing the field strength to== 2500 Oe, a χ″(ν) growth is observed at all magnetic field strengths applied for the measurements, but 2500 Oe,Oe, χ″(ν) growth observed atall all magnetic field strengths applied forthe thethe measurements, but Oe, aaχ″(ν) isisobserved at field strengths applied for measurements, but H2500 = 2500 a χ00growth (ν) growth is observed atmagnetic all magnetic field strengths applied for measurements, no maximum was found on the χ″(ν) plots (Figure S9). no maximum was found on the χ″(ν) plots (Figure S9). no maximum was found on the χ″(ν) plots (Figure S9). 00 but no maximum was found on the χ (ν) plots (Figure S9). The study ofofbinuclear Complexes 1–4 that we has that 2 has the Thestudy study binuclear Complexes 1–4 that weperformed performed hasshown shown thatComplex Complex has the The study binuclear Complexes that performed shown Complex has the The ofof binuclear Complexes 1–41–4 that wewe performed has has shown that that Complex 2 has22the best best SMM characteristics, whereas no SMM properties were found in Complex 3. Interestingly, the best SMM characteristics, whereas no SMM properties were found in Complex 3. Interestingly, the best SMM characteristics, whereas no SMM properties were found in Complex 3. Interestingly, the SMM characteristics, whereas no SMM properties were found in Complex 3. Interestingly, the lowering lowering of number in pairs 111and 2,2,2,and 333and 444takes place. The lowering ofthe thecoordination coordination number inthe thecorresponding corresponding pairs and and and takes place. The lowering of the coordination in the corresponding pairs and and and takes place. The of the coordination number innumber the corresponding pairs 1 and 2, and 3 and 4 takes place. The results results obtained agree with the concept that changes in local molecular symmetry and even results obtained obtained agree with the the concept that changes in local local molecular symmetry and even even results agree with concept that in molecular symmetry and obtained agree with the concept that changes in changes local molecular symmetry and even insignificant insignificant distortion of coordination geometry [41], as well as possible dipole coupling of Dy(III) insignificant distortion of coordination geometry [41], as well as possible dipole coupling of Dy(III) insignificant distortion of coordination geometry [41], as well as possible dipole coupling of Dy(III) distortion of coordination geometry [41], as well as possible dipole coupling of Dy(III) ions [42] have ions [42] aaaconsiderable effect characteristics. The enhancement ofofSMM properties ions [42]have haveeffect considerable effecton onSMM SMM characteristics. The enhancement SMM properties [42] have considerable effect on SMM characteristics. enhancement SMM aions considerable on SMM characteristics. The enhancement The of SMM propertiesof with theproperties lowering with the lowering of the coordination number observed in our case is in agreement with the with the lowering of the coordination number observed in our case is in agreement with therecent recent with the lowering of the coordination number observed in our case is in agreement with the recent of the coordination number observed in our case is in agreement with the recent theoretical study [43]. theoretical study [43]. theoretical study [43]. theoretical study [43]. 2 Studies of polymeric complex [Dy(η -O CCym) (µ-O CCym) Dy(H O) ] (5) (whose molecular 2 2 2 4 2 4 n 22-O 2-O Studies of complex [Dy(η 22CCym) 22(μ-O 22CCym) 44Dy(H 22О) 44]] (whose molecular Studies ofpolymeric polymeric complex [Dy(η -O 2CCym) CCym) 2(μ-O (μ-O 2CCym) CCym) 4Dy(H Dy(H 2О) О) 4n]nn(5) (5) (whose molecular Studies of polymeric complex [Dy(η (5) (whose molecular structure is shown in Figure 4) were performed previously [21]. Maxima were observed in structure is shown in Figure 4) were performed previously [21]. Maxima were observed in the structure is shown in Figure 4) were performed previously [21]. Maxima were observed in thezero zero structure is shown in Figure 4) were performed previously [21]. Maxima were observed in the zero 00 the zero field on the frequency dependences of out-of-phase component χ at low temperatures field frequency dependences of component temperatures fieldon onthe the frequency dependences ofout-of-phase out-of-phase componentχ″ χ″at atlow low temperatures(2–3 (2–3K), K),which which field on the frequency dependences of out-of-phase component χ″ at low temperatures (2–3 K), which (2–3 K), which confirms the presence of slow relaxation of the magnetization (Figure S10). confirms the presence of slow relaxation of the magnetization (Figure S10). Analysis of the isotherms confirms the presence of slow relaxation of the magnetization (Figure S10). Analysis of the isotherms confirms the presence of slow relaxation of the magnetization (Figure S10). Analysis of the isotherms Analysis of the isotherms of frequency dependences gave the relaxation time. Figure S11 shows of gave the relaxation time. shows the of offrequency frequencydependences dependences gave theon relaxation time.Figure FigureS11 S11the shows thedependence dependence ofrelaxation relaxation of frequency dependences gave the relaxation Figure S11 shows the dependence of relaxation the dependence of relaxation time inverse time. temperature in temperature range of 2.0–3.5 K. time on inverse temperature in the temperature range of 2.0–3.5 K. Using the Arrhenius law τττ=== time on inverse temperature in the temperature range of 2.0–3.5 K. Using the Arrhenius law time on inverse temperature in the temperature range of 2.0–3.5 K. Using the Arrhenius law − 6 Using the Arrhenius law τ = τ0 ·exp(∆E/kB T), the pre-exponential factor (τ0 = 4.3 × 10 s) and −6 −6 −6 ττ0τ0∙exp(ΔE/k BBT), the factor (τ 00= 4.3 s)s)s)and BBB === 0·exp(ΔE/k ·exp(ΔE/k BT), T),energy thepre-exponential pre-exponential factor (τ 0== 4.3×××10 10 andthe therelaxation relaxationenergy energybarrier barrier(ΔE/k (ΔE/k the pre-exponential factor (τ 4.3 10 and the relaxation energy barrier (ΔE/k the relaxation barrier (∆E/k B = 4.1 K) were determined. The shape of ln(τ) vs. (1/T) 4.1 determined. The ofofln(τ) vs. and χ″(χ′) (Figure S12) allow 4.1K) K) were determined. Theshape shape ln(τ) vs.(1/T) (1/T) andrelaxation χ″(χ′)plots plots (Figure S12)activated allowus usto tobelieve believe 4.1 K) were determined. shape vs. (1/T) and χ″(χ′) plots S12) allow us to believe 00were 0 ) plots and χ (χ (Figure The S12) allowof usln(τ) to believe that is(Figure thermally and that that relaxation is thermally activated and that a purely quantum mode takes place below the that relaxation is thermally activated and that a purely quantum mode takes place below the that relaxation is thermally activated and that a purely quantum mode takes place below the a purely quantum mode takes place below the temperature studied (T < 2 K). 2A unit of the 2 2 temperature studied (T < 2 K). A unit of the polymeric chain [Dy(η -O 2 CCym) 2 temperature studied (T < 2 K). A unit of the polymeric chain [Dy(η -O CCym) 2(μ(μtemperature studied (T < 2 K). A unit of the polymeric chain [Dy(η -O 22CCym) 2(μ2 polymeric chain [Dy(η -O2 CCym)2 (µ-O2 CCym)4 Dy(H2 O)4 ]n (5) contains two Dy atoms, one of which O 22CCym) 44Dy(H 22О) 44]] contains two Dy atoms, one of which coordinates four O atoms of {μO 2CCym) CCym) 4Dy(H Dy(H 2О) О) 4n]nn(5) (5) contains two Dy atoms, one of which coordinates four O atoms of {μO (5) contains two Dy atoms, one of which coordinates four O atoms of {μcoordinates four O atoms of {µ-O2 CCym) ligands and four O atoms of H2 O molecules (Figure 4). O 2 CCym) ligands and four O atoms of H 2 O molecules (Figure 4). The second Dy atom coordinates CCym) ligands and fourOOatoms atoms of H Omolecules molecules (Figure4). 4).The Thesecond secondDy Dyatom atom2coordinates coordinates OO22CCym) and four 22O (Figure The secondligands Dy atom coordinates fourof OH atoms of {µ-O 2 Ccym} and four O atoms of {η -O2 CCym} 22-O 2-O four O atoms of {μ-O 22Ccym} and four O atoms of {η 22CCym} ligands. The coordination number four O atoms of {μ-O 2Ccym} Ccym} and four O atoms of {η -O 2CCym} CCym} ligands. The coordination numberof of four O atoms of {μ-O and four O atoms of {η ligands. The coordination number of ligands. The coordination number of Dy atoms is eight; the {Dy(µ-O2 CCym)4 (H2 O)4 } polyhedron is 22-2 Dy 22CCym) 44(H 22O) 44}4}}polyhedron Dyatoms atomsisisiseight; eight;the the{Dy(μ-O {Dy(μ-O 2CCym) CCym) 4(H 2O) O) polyhedronisisisaaatwo-cap two-captrigonal trigonalprism. prism.The The{Dy(η {Dy(η Dy atoms eight; the {Dy(μ-O (H polyhedron two-cap trigonal prism. The {Dy(η -O 2 CCym) 2 (μ-O 2 CCym) 4 } polyhedron is strongly distorted and is most similar to a trigonal CCym)22(μ-O (μ-O22CCym) CCym)44}} polyhedron polyhedron isis strongly strongly distorted distorted and and isis most most similar similar to to aa trigonal trigonal OO22CCym) 22-O 2-O dodecahedron 22C dodecahedronwith withthe thecentral centralsegments segmentsof ofthe thetrapezohedra trapezohedraoccupied occupiedby byηηη -O 2C Cmoieties. moieties.ItItIthas hasbeen been dodecahedron with the central segments of the trapezohedra occupied by moieties. has been shown [44] that the existence of magnetic centers with differing anisotropy can give rise to two shown [44] [44] that that the the existence existence of of magnetic magnetic centers centers with with differing differing anisotropy anisotropy can can give give rise rise to to two two shown


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a two-cap trigonal prism. The {Dy(η2 -O2 CCym)2 (µ-O2 CCym)4 } polyhedron is strongly distorted and is most similar to a trigonal dodecahedron with the central segments of the trapezohedra occupied by η2 -O2 C moieties. It has been shown [44] that the existence of magnetic centers with differing anisotropy Magnetochemistry 2016, 2, 38 10 of 15 can give rise to two different mechanisms of magnetic relaxation that correspond to two different positions mechanisms of dysprosiumofatoms. Though Structure 5 contains two crystallographically different Dy different magnetic relaxation that correspond to two different positions of centers, studies haveThough shown Structure that only one mechanism thermally-activated magnetic dysprosium atoms. 5 contains two of crystallographically different Dyrelaxation centers, is present. studies have shown that only one mechanism of thermally-activated magnetic relaxation is present. The structure structure of of a polymeric complex [Dy(O CCym)(acac)22(H (H22O)] O)]n n(6) (6)isisformed formedby by polymeric polymeric The [Dy(O22CCym)(acac) chains(Figure (Figure5); 5);the thecoordination coordinationnumber numberof ofDy Dyisisseven; seven;the thepolyhedron polyhedronisisaapentagonal pentagonalbipyramid. bipyramid. chains Previously, incomplete incompletestudy studyofofthis thiscomplex complexwas wascarried carried out [21]. The temperature dependences Previously, out [21]. The temperature dependences of of the out-of-phase alternating-current magnetic susceptibility the external zero external magnetic the out-of-phase alternating-current (ac) (ac) magnetic susceptibility in theinzero magnetic field field obtained. were obtained. However, no application of an external was made. In this were However, no application of an external magneticmagnetic field was field made. In this study, the study, the dynamics of the magnetization was probed by ac susceptibility measurements dynamics of the magnetization was probed by ac susceptibility measurements for Complex 6. Atfor 2 Complex 6. At 2 K,mode an acfor relaxation mode for 6 2000 appears 2000 Oe. From the of complete K, an ac relaxation 6 appears around Oe. around From the complete study the ac study of the ac as a functionand of temperature 2000 (Figure 11), susceptibility as susceptibility a function of temperature frequency at and 2000frequency Oe (Figureat11), theOe characteristic the characteristic time of the magnetization was estimated between 2 and 10 K relaxation time ofrelaxation the magnetization was estimated between 2 and 10 K (Figure S15). As(Figure shownS15). by As shown by the non-thermally-activated dependence of thetime relaxation in this temperature range, the non-thermally-activated dependence of the relaxation in this time temperature range, quantum quantum of tunneling of the magnetization is dominating obviously dominating the process relaxation in 6 even tunneling the magnetization is obviously the relaxation in 6process even under the under the dc field. Nevertheless, to extrapolate the Arrhenius 10toK applied dcapplied field. Nevertheless, an attemptan toattempt extrapolate the Arrhenius behavior behavior above 10 above K leads −7 toestimation a rough estimation of the SMM energy gap 42 of K, about with a pre-exponential factor aleads rough of the SMM energy gap of about with42a K, pre-exponential factor of 4.3 × 10of − 7 × value 10 s.ofThe value of τ0least , which is orders at least of four orders oflarger magnitude larger than for typical s.4.3 The τ0, which is at four magnitude than expected forexpected typical vibrations vibrations of thefurther network, furtherthat confirms that the estimation valueB should of ∆E/kbe be considered as of the network, confirms the estimation value of ΔE/k considered as a lower B should a lower limit of the actual energy barrier for the thermally-activated relaxation process in 6. limit of the actual energy barrier for the thermally-activated relaxation process in 6.

(a)

(b)

Figure Figure 11. 11. Frequency Frequencydependence dependenceofofthe the in-phase in-phase (χ′, (χ0 , a)a) and and out-of-phase out-of-phase (χ″, (χ00 , b) b) parts parts of of ac ac susceptibility, between 2 and 10 K, for 6 in a 2000 Oe dc field. Solid lines are visual guides. susceptibility, between 2 and 10 K, for 6 in a 2000 Oe dc field. Solid lines are visual guides.

To give a fuller picture, we also present our data [24] for ferrocenoylacetonate To give a fuller picture, we also present our data [24] for ferrocenoylacetonate [Dy(fca)3(bpy)]∙MeC6H5 (7). The structure of 7 contains the [Dy(fca)3(bpy)] complex (Figure 6) and [Dy(fca)3 (bpy)]·MeC6 H5 (7). The structure of 7 contains the [Dy(fca)3 (bpy)] complex (Figure 6) and solvate molecules of MeC6H5. Bpy…bpy stacking interactions bind complexes into centrosymmetric solvate molecules of MeC6 H5 . Bpy. . . bpy stacking interactions bind complexes into centrosymmetric dimers. The solvate molecule of MeC6H5 that is arranged in rather a spacious cavity is not involved dimers. The solvate molecule of MeC6 H5 that is arranged in rather a spacious cavity is not involved in stacking interactions. Detailed studies of dc and ac magnetic susceptibility were carried out. SMM in stacking interactions. Detailed studies of dc and ac magnetic susceptibility were carried out. properties were detected at temperatures up to 32 K. Most likely, owing to the electron-donating SMM properties were detected at temperatures up to 32 K. Most likely, owing to the electron-donating effect of ferrocenyl moieties [45,46], the complex has an extremely high magnetization reversal effect of ferrocenyl moieties [45,46], the complex has an extremely high magnetization reversal barrier, barrier, Δeff/kB = 241 K, which is a record value for lanthanide β-diketonates. This result illustrates the ∆eff /kB = 241 K, which is a record value for lanthanide β-diketonates. This result illustrates the importance of the effect of the crystal field on the SMM properties of dysprosium complexes. importance of the effect of the crystal field on the SMM properties of dysprosium complexes. 3. Experimental Section 3.1. Materials and Methods The following commercial reagents and solvents were used for the syntheses: hydrated dysprosium salts Dy(NO3)3 5H2O, DyCl3.6H2O and acetylacetonate Dy(acac)3∙3H2O, from Alfa Aesar (Heysham, Lancashire, UK), cymantrene from Aldrich (St. Louls, MO, USA), acetylferrocene (Alfa Aesar, 97%) and solvents (MeOH, DMSO, C6H5Me, CHCl3, C2H5OH) from Alfa Aesar.


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3. Experimental Section 3.1. Materials and Methods The following commercial reagents and solvents were used for the syntheses: hydrated dysprosium salts Dy(NO3 )3 5H2 O, DyCl3 . 6H2 O and acetylacetonate Dy(acac)3 ·3H2 O, from Alfa Aesar (Heysham, Lancashire, UK), cymantrene from Aldrich (St. Louls, MO, USA), acetylferrocene (Alfa Aesar, 97%) and solvents (MeOH, DMSO, C6 H5 Me, CHCl3 , C2 H5 OH) from Alfa Aesar. Cymantrenecarboxylic acid was synthesized according to a known procedure by the reaction of cymantrenyllithium obtained from n-butyllithium and cymantrene in THF at −45 ◦ C, with solid CO2 [47]. Before use in the synthesis, cymantrenecarboxylic acid was sublimed in vacuo to remove traces of Mn2+ . Methanol was dehydrated before use by distillation over magnesium; toluene was successively distilled over P2 O5 and sodium; DMSO was purified by freezing. Magnetic susceptibility measurements were performed with the use of a Quantum Design magnetometer/susceptometer PPMS-9 (Quantum Design, San Diego, CA, USA). This instrument works between 1.8 and 350 K for dc applied fields ranging from −9 to 9 T. For ac susceptibility measurements, an oscillating ac field of 1 or 5 Oe with a frequency between 10 and 10,000 Hz was employed. Measurements were performed on polycrystalline samples sealed in polyethylene bags and covered with mineral oil in order to prevent field-induced torqueing of the crystals. The magnetic data were corrected for the sample holder, mineral oil and diamagnetic contribution. X-ray powder diffraction analysis was carried out on a Bruker D8 ADVANCE X-ray diffractometer (CuKα , Ni-filter, LYNXEYE detector, reflection geometry) (Bruker, Karslruhe, Germany). Experimental data from single crystals were obtained on a Bruker SMART APEX2 diffractometer [48] (Table S1). Absorption for 3 and 4 was taken into account by a semiempirical method based on equivalents using SADABS software [49]. For Compound 3, the model of the isostructural Tb complex was used [23]. The positions of hydrogen atoms were calculated from geometrical considerations and refined using the “riding” model. The structure of 4 was determined using a combination of the direct method and Fourier syntheses. The structures of 3 and 4 were refined by the full-matrix anisotropic-isotropic least squares method. All of the calculations were carried out using SHELXS-2014 and SHELXL-2014 software [50]. CCDC 1493047 and 1493048 contain the supplementary crystallographic data for Compounds 3 and 4. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, U.K.; fax: (+44) 1223-336-033; or e-mail: [email protected]. 3.2. Synthesis of Complexes 1–4 Dysprosium complexes [Dy2 (O2 CCym)6 (DMSO)4 ] (1), [Dy2 (O2 CCym)4 (NO3 )2 (DMSO)4 ] (2) and [Dy(O2 CCym)(acac)2 (H2 O)]n (5) were synthesized using the procedures that we developed previously [18,22]. The complex [Dy2 (O2 CFc)4 (NO3 )2 (DMSO)4 ] (3) was prepared according to the procedure used for the synthesis of its Gd and Tb isostructural analogs [23]. The complex [Dy2 (O2 CFc)6 (DMSO)2 (H2 O)2 ]·2DMSO·3MePh (4) was obtained according to the procedure reported previously for the complex [Gd2 (O2 CFc)6 (DMSO)2 (H2 O)2 ]·2DMSO·2CH2 Cl2 [23], except that boiling toluene (25 mL) was used for the extraction of the substance, and the resulting solution was kept at 4 ◦ C for two days. 4. Conclusions In summary, we have obtained new findings on the magnetism of the lanthanide complexes with stable organometallic ligands. The analysis of complementary data on exchange coupling in binuclear complexes of gadolinium with two bridging oxygen atoms has shown the validity of the correlation between JGd-Gd0 and the Gd. . . Gd distance that we suggested earlier. Dynamic ac magnetic susceptibility measurements have shown that the presence of more than one dysprosium atom in a molecule adversely affects the molecular magnet properties, since, as a rule,


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SMM properties in polynuclear SMM are demonstrated by each lanthanide atom rather than by the exchange coupled systems as in complexes of d-elements. A considerable drawback of polynuclear lanthanide complexes lies in the existence of dipole-dipole coupling that accelerates relaxation processes and in their tendency to quantum tunneling, which noticeably decreases the real relaxation times. Furthermore, SMM characteristics are considerably affected by changes in local molecular symmetry and even insignificant distortion of coordination geometry. It has been shown also that the Magnetochemistry 2016, 2, 38 Magnetochemistry 2016, 2, 38 increase of the coordination number weakens the SMM properties of similar Dy complexes.

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Supplementary Materials: The following online Table Supplementary Materials: The following areavailable available online at at www.mdpi.com/2312-7481/2/4/38/s1: www.mdpi.com/2312-7481/2/4/38/s1: S1:S1: Supplementary Materials: The following are availableare online at www.mdpi.com/2312-7481/2/4/38/s1. Table S1:Table 2312-7481/2/4/38/s1:Crystal Table S1: Crystal data andand structure refinement S1: χT vs. temperature for 1–4((∇, (∇, [18]; Crystal data structure refinement for3,3,4,4,Figure Figure S1:Plots Plots ofvs. χT vs. temperature for 1–4 ▲,▲, 2; 2; ο, ο, 3; 3; data and structure refinement for 3, 4, for Figure S1: Plots of χTof temperature for 1–4 , 111[18]; [18]; re for 1–4 (∇, 1 [18]; N ▲, 2; ο,, 3; The measurements were field H 5000 Oe, Figure S2: Frequency , 2; 3; ■,, 4). The measurements were carried out in an external magnetic field fieldH H===5000 5000Oe, Oe,Figure Figure S2: ■, 4). The measurements werecarried carriedout outin inan anexternal external magnetic magnetic S2: Frequency 0 , a) and out-of-phase (χ00 , b) parts of the ac susceptibility, between 2 Frequency dependences dependences of the thethe in-phase (χ(χ′, 00 Oe, Figure S2: Frequency of in-phase (χ′, a)a)and ac susceptibility, susceptibility,between between2 2and and 6 K, dependences of in-phase andout-of-phase out-of-phase(χ″, (χ″,b) b) parts parts of the ac 6 K, forfor and 6 K, for [Dy (O CCym) (DMSO) ] (1) in thedczero dc(this field (this Solid study). Solid lines guides, are visual guides, 2 2 6 4 ibility, between 2 and 6 K, for [Dy[Dy 2(O2(O CCym) 6(DMSO) 4] (1) inin the zero field study). lines are visual guides, Figure S3: Frequency 2CCym) 6(DMSO) 4] (1) the zero dc field (this study). Solid lines are visual Figure S3: Frequency Figure S3: Frequency dependences of the in-phase (χ0 , a) and out-of-phase (χ00 , b) parts of the ac susceptibility, dependences in-phase(χ′, (χ′,a)a)and and out-of-phase out-of-phase (χ″, (χ″, b) parts parts of guides, Figure S3: Frequency of of thethein-phase of the the ac ac susceptibility, susceptibility,atat2 2K,K,forfor at 2 K, fordependences [Dy2 (O2 CCym) 6 (DMSO)4 ] (1) in the zero, 1000 and 2000 Oe dc field (this study). Solid lines [Dy 2CCym) 6(DMSO) ]− (1) inthe thezero, zero,1000 1000and and2000 2000 Oe Oe dc dc field (this study). Solid lines are c susceptibility, at are 2 K, for [Dy 2(O22(O CCym) 6(DMSO) 4] 4(1) in (this study). Solid lines arevisual visualguides, guides, 1 visual guides, Figure S4: −1 τ vs. T plot for [Dy2 (O2 CCym)4 (NO3 )2 (DMSO)4 ] (2) in the zero magnetic −1Tplot plot for [Dy 2(O 2CCym) 4(NО 2(DMSO)44]] (2) (2) in in−the the zero magnetic field. The solid red line is is Figure S4: τ vs. Solid lines are visual guides, 9 for [Dy 2(O 2CCym) 4(NО 3)32)(DMSO) zero magnetic field. The solid red line Figure S4: τ vs. T field. The solid red line is the best fit to the Arrhenius law (τ = 3.2·10 s, ∆E/kB = 53 K) (this study), −9 s, ΔE/kB =053 K) (this study), 0 = 3,2·10 Figure S5: dependences of of fit the to the Arrhenius law 00 , b) parts etic field. The solid red lineS5: is Frequency 0 = 3,2·10 s, and ΔE/kout-of-phase B = 53 K) (this Figure S5:Frequency Frequency dependences the the bestbest fit dependences to Arrhenius law (τ(τ Figure of the in-phase (χ0−9 , a) (χstudy), of the ac susceptibility, the (χ′,a) a)2 CCym) andout-of-phase out-of-phase (χ″, b) b) parts of the ac acOesusceptibility, and betweenof4the and 5 in-phase K, for(χ′, [Dy (2) inof a the 1000 dc field (thisbetween study). 4 4Solid 5: Frequency dependences in-phase (χ″, susceptibility, between and5 5K,K,forfor 2 (Oand 4 (NO3 )2 (DMSO) 4 ] parts 0 ,Solid 00 , b) [Dy 2(O2CCym) 4(NО 3)2(DMSO) 4] (2) dependences in a 1000 Oe dc field (this study). lines are visual guides, S6:S6: lines are visual guides, Figure S6: Frequency of the in-phase (χ a) and out-of-phase (χ y, between 4 and 5 K, for [Dy2(O2CCym)4(NО3)2(DMSO)4] (2) in a 1000 Oe dc field (this study). Solid lines are visual guides,Figure Figure parts of the acFrequency susceptibility, between 2the and 4 K, for [Dy (O2out-of-phase CFc)4 (NO3 )(χ″, (DMSO) ] of (3)the in ac thesusceptibility, zero dc fieldbetween 2 dependences of in-phase (χ′, a) and b) parts 2 2 4 are visual guides, Figure S6: Frequency dependences of the in-phase (χ′, a) and out-of-phase (χ″, b) parts of the ac susceptibility, between 2 (this study). and Solid lines are2(O visual Figure4]S7: Frequency of the (χ0 , a)guides, and Figure 2CFc)guides, 4(NO3)2(DMSO) (3) in the zero dcdependences field (this study). Solidin-phase lines are visual 4 K, for [Dy e ac susceptibility, between 2 2(O2CFc)4(NO3)2(DMSO)4] (3) in the zero dc field (this study). Solid lines are visual guides, Figure and 4 K, for [Dy 00 out-of-phase (χ b) parts ofdependences the ac susceptibility, between andout-of-phase 24 K, for [Dy CFc)4of(NO )2 (DMSO) 4 ] (3) between S7:,Frequency of the in-phase (χ′, a)2and (χ″,2 (O b)2parts the3ac susceptibility, lines are visual guides, S7:dc Frequency dependences of the in-phase (χ′, a)guides, and out-of-phase b) parts of the ac susceptibility, in aFigure 5000 Oe field (this study). Solid lines are visual Figure S8:(χ″, Frequency dependences of the between 2 and 24 K, for [Dy2(O002CFc)4(NO3)2(DMSO)4] (3) in a 5000 Oe dc field (this study). Solid lines are visual guides, a) and , b) parts of the ac4]susceptibility, at 2dc K,field for [Dy (NO3lines )2 (DMSO) the ac susceptibility,in-phase between(χ20 , and 24 out-of-phase K, for [Dy2(O(χ 2CFc) 4(NO 3)2(DMSO) (3) in a 5000 Oe (this study). are visual guides, 2 (O 2 CFc)4Solid 4] Figure S8:1000 Frequency dependences of the(this in-phase (χ′, a)Solid and out-of-phase (χ″, b) guides, parts of the ac susceptibility, (3)guides, in the Figure zero, 500, and dependences 1500 Oe dc of field study). lines are visual Figure S9: Solid lines are visual S8: Frequency the in-phase (χ′, a) and out-of-phase (χ″, b) parts of the ac susceptibility, 0 , a) and at 2 K, for [Dy 4(NO3)(χ 2(DMSO) 4] (3) in the zero, 500, and 1500 Oe ac dc susceptibility, field (this study). Frequency dependences of2(O the2CFc) in-phase out-of-phase (χ00 ,1000 b) parts of the at Solid 2 K, lines are parts of the ac susceptibility, at 2 K, for [Dy2(O2CFc)4(NO3)2(DMSO)4] (3) in the zero, 500, 1000 and 1500 Oe dc field (this study). Solid lines are visual guides, Figure S9: Frequency dependences of the in-phase (χ′, a) and out-of-phase (χ″, b) parts for [Dy2 (O2 CFc)6 (DMSO)2 (H2 O)2 ] (4) in the zero, 1000, 1500, 2000 and 2500 Oe dc-field (this study). Solid lines of the ac eld (this study). Solidare lines are guides, visual guides, S9:forFrequency dependences of the in-phase (χ′, a)out-of-phase and out-of-phase (χ″, Oe b) the ac visual FigureFigure S10: dependences of the (a) and1000, of parts the of (this susceptibility, at 2 Frequency K, [Dy2(O 2CFc)6(DMSO) 2(H 2O)in-phase 2] (4) in the zero, 1500, 2000 (b) andparts 2500 dc-field 2 f-phase (χ″, b) partsacofsusceptibility the ac susceptibility, at 2 K, for [Dy 2(O2CFc)6(DMSO)2(H2O)2] (4) in the zero, 1000, 1500, 2000 and 2500 Oe dc-field (this of [Dy(η Figure S11:(a)Plot ln(τ) study). Solid -O lines are visual guides, Figure S10:2 O) Frequency dependences of the in-phase andof out-of-phase (b) 2 CCym) 2 (µ-O 2 CCym) 4 Dy(H 4 ]n (5) (H dc = 0 Oe) [21], 2 -OSolid 00 in S11: Plot(b) 000 and 2500 Oe dc-field (this[Dy(η study). lines are 2visual guides, Figure S10: Frequency dependences the(H in-phase (a)[21], and out-of-phase 2 ]2CCym) vs. 1/T CCym) Dy(H from the frequency dependences ofFigure χ 2(μ-O2CCym) 4Dy(H 2О)4]of n (5) dc = 0 Oe) parts of the ac2 (µ-O susceptibility [Dy(η 2 CCym) 4of 2 O)-O 4 n (5) obtained 2 2-O phase (a) and out-of-phase (b)magnetic 2CCym) 2(μ-O 2CCym) 4Dy(H 2О) 4]6 n (H (5) (H 0 Oe) [21], S11: Plot parts thevs. ac susceptibility ofCole-Cole [Dy(η the zero field [21], Figure S12: dependence for (O (Hdependences = 0Figure Oe), of of of ln(τ) 1/T [Dy(η 2CCym) 2(μ-O-O 2CCym) 4Dy(H 2О) 4]n[Dy (5) 2obtained from the frequency χ″ in 2 CCym) 2 O) 4dc]n= (5) DC 2-O2CCym) S13:ofFrequency dependences of the in-phase (a) and out-of-phase (b) parts of the ac susceptibility of = 0 Oe) [21], FigureFigure S11: Plot ln(τ) vs. 1/T [Dy(η 2 (μ-O 2 CCym) 4 Dy(H 2 О) 4 ] n (5) obtained from the frequency dependences of χ″ the zero magnetic field [21], Figure S12: Cole-Cole dependence for [Dy2(O2CCym)6(H2О)4]n (5) (HDC = 0 Oe), in [Dy(CymCO (H2 O)] (6) (H[21], = 0Figure Oe) (this study), Figure(a) S14: Frequency dependences of the out-of-phase n field 2 )(acac) 2S13: dc equency dependences of χ″ in 2(O 2CCym) 6(H 2О)ac 4]n susceptibility (5) (HDC = 0 Oe), the zero magnetic S12: Cole-Cole for [Dy Figure Frequency dependences of the in-phasedependence and out-of-phase (b) parts of of (χ00 ) parts of the ac susceptibility at 2.3 K, for [Dy(CymCO2 )(acac)2 (H2 O)]n (6) in the zero, 1000 and 2000 Oe dc m)6(H2О)4]n (5) (HDC = 0 Oe), Figure S13: Frequency dependences (a) and out-of-phase (b)dependences parts of theofac susceptibility [Dy(CymCO 2)(acac)2(H 2O)]n (6) (Hdc of = 0 the Oe) in-phase (this study), Figure S14: Frequency out-of-phase (χ″) of − 1 field (this study). Solid lines are visual guides, Figure S15: τ vs. T plot for [Dy(CymCO2 )(acac)2 (H2 O)]n (6) in 2(H 2O)] n (6) in thedependences zero, 1000 and Oe dc field parts of the ac susceptibility 2.3 K,0 for [Dy(CymCO rts of the ac susceptibility of dc [Dy(CymCO 2)(acac) 2O)]n (6)at dc = Oe) (this study),2)(acac) Figure S14: Frequency of2000 out-of-phase (χ″) a 2000 Oe field. The solid red2(H line is the (H best fit to the Arrhenius law (this study). −1 plot for [Dy(CymCO2)(acac)2(H2O)]n (6) in a 2000 (this study). Solid lines are visual guides, Figure S15: τ vs. T endences of out-of-phase (χ″) parts of the ac susceptibility at 2.3 K, for [Dy(CymCO2)(acac)2(H2O)]n (6) in the zero, 1000 and 2000 Oe dc field Acknowledgments: This study wasare financially supported the Russian Science (Grant 14-13-00938). dc field. Thelines solid red line is the best fit to by theS15: Arrhenius (this study). ro, 1000 and 2000 Oe dc field (thisOestudy). plot forFoundation [Dy(CymCO 2)(acac)2(H2O)]n (6) in a 2000 Solid visual guides, Figure τ vs. T−1law Contributions: P.S.K. andred A.V.G. the complexes. N.N.E. P.S.K. performed the experiments. O2)(acac)2(H2O)]n (6)Author in a 2000 Oe Acknowledgments: dc field. The solid linesynthesized isstudy the best fit tofinancially the Arrhenius lawand (this study). This was supported by the Russian Science Foundation A.B.I performed the structural experiments. Z.V.D. conceived of and designed the experiments. Z.V.D., P.S.K. and (Grant 14-13-00938). Acknowledgments: This study was financially supported by the Russian Science Foundation N.N.E. wrote the paper. V.M.N. supervised and managed the project. ussian Science Foundation (Grant 14-13-00938). Author The Contributions: P.S.K. and A.V.G. synthesized the complexes. N.N.E. and P.S.K. performed the Conflicts of Interest: authors declare no conflict of interest. experiments. A.B.I performed the structural experiments. Z.V.D. conceived of and designed the experiments. Author Contributions: P.S.K. and A.V.G. synthesized the complexes. N.N.E. and P.S.K. performed the Z.V.D., P.S.K. and N.N.E. wrote the paper. V.M.N. supervised and managed the project. . and P.S.K. performed the experiments. A.B.I performed the structural experiments. Z.V.D. conceived of and designed the experiments. References Conflicts Interest: The authors no conflict of interest. nd designed the experiments. Z.V.D., P.S.K.ofand N.N.E. wrote the declare paper. V.M.N. supervised and managed the project. Caneschi, A.; Gatteschi, R.; Sessoli, R.; Barra, A.L.; Brunel, L.C.; Guillot, M. Alternating current 1. roject. Conflictshigh of Interest: The authors declare no conflict of interest. susceptibility, Referencesfield magnetization, and millimeter band EPR evidence for a ground S = 10 state in [Mn12 O12 (CH3 COO)16 (H2 O)4 ]·2CH3 COOH·4H2 O. J. Am. Chem. Soc. 1991, 113, 5873–5874. [CrossRef] 1. Gatteschi, Caneschi, Gatteschi, R.; Sessoli, Barra, bistability A.L.; Brunel, L.C.; Guillot, M. Nature Alternating References 2. Sessoli, R.; D.; A.; Caneschi, A.; Novak, M.A. R.; Magnetic in a metal-ion cluster. 1993, current susceptibility, high field magnetization, and millimeter band EPR evidence for a ground S = 10 state in 365, 141–142. [CrossRef] 1. Caneschi, R.;4]·2CH Sessoli, R.; Barra, A.L.; Brunel, L.C.; Guillot, M. Alternating current (CH3Gatteschi, COO)16(H2O) 3COOH·4H2O. J. Am. Chem. Soc. 1991, 113, 5873–5874. [Mn12O12A.; Sessoli, R.;susceptibility, Powell, A.K. Strategies towards single molecule magnets on for lanthanide ions. lot, M. Alternating3. current high field magnetization, and millimeter bandbistability EPRbased evidence a ground = 10 state 2. Sessoli, R.; Gatteschi, D.; Caneschi, A.; Novak, M.A. Magnetic in a metal-ion cluster.SNature 1993, in Coord. Chem. Rev. 2009, 253, 2328–2341. [CrossRef] e for a ground S = 10 state in 12 O 12 (CH 3 COO) 16 (H 2 O) 4 ]·2CH 3 COOH·4H 2 O. J. Am. Chem. Soc. 1991, 113, 5873–5874. [Mn 365, 141–142. 4. Bünzli, Lanthanide coordination chemistry: From old concepts to coordination polymers. 5873–5874. 2. J.-C.G. R.;R.; Gatteschi, D.; Caneschi, Novak, M.A. Magnetic bistability inon a metal-ion Nature 1993, 3. Sessoli, Sessoli, Powell, A.K. StrategiesA.; towards single molecule magnets based lanthanidecluster. ions. Coord. Chem. J. Coord. Chem. 2014, 67, 3706–3733. [CrossRef] metal-ion cluster. Nature 1993, 365,Rev. 141–142. 2009, 253, 2328–2341. 5. Castro, Regueiro-Figueroa, M.;Strategies Esteban-Gomez, D.; Perez-Lourido, P.; Platas-Iglesias, C.; Valencia, 3. G.; R.;J.-C.G. Powell,Lanthanide A.K. towardschemistry: single molecule magnets based on lanthanide ions. L. Coord. Chem. 4. Sessoli, Bünzli, coordination From old concepts to coordination polymers. J. Coord. Magnetic anisotropies in rhombic lanthanide(III) complexes do not conform to bleaney’s theory. Inorg. Chem. lanthanide ions. Coord. Chem. Rev.Chem. 2009,2014, 253, 67, 2328–2341. 3706–3733. 2016, 55, 5. 3490–3497. [CrossRef] [PubMed] M.; Esteban-Gomez, D.; Perez-Lourido, P.; Platas-Iglesias, C.; Valencia, L. Castro, G.; Regueiro-Figueroa, 4. Bünzli, J.-C.G. Lanthanide coordination chemistry: From old concepts to coordination polymers. J. Coord. Magnetic anisotropies in rhombic lanthanide(III) complexes do not conform to bleaney’s theory. Inorg. ordination polymers. J. Coord. Chem. 2014, 67, 3706–3733. Chem. 2016, 55, 3490–3497. 5. Castro, G.; Regueiro-Figueroa, M.; Esteban-Gomez, D.; Perez-Lourido, P.; Platas-Iglesias, C.; Valencia, L. 6. Magnetic Gregson, M.; Chilton,in N.F.; Ariciu, lanthanide(III) A.-M.; Tuna, F.; Crowe, I.F.; Lewis, Blake, A.J.; Collison, D.; McInnes, latas-Iglesias, C.; Valencia, L. anisotropies rhombic complexes do notW.; conform to bleaney’s theory. Inorg. E.J.L.; Winpenny, R.E.P.; et al. A Monometallic Lanthanide Bis(methanediide) Single molecule magnet with m to bleaney’s theory. Inorg. Chem. 2016, 55, 3490–3497. a largeM.; energy barrier andAriciu, complex spin Tuna, relaxation behaviour. Chem. Sci. 7, A.J.; 155–165. 6. Gregson, Chilton, N.F.; A.-M.; F.; Crowe, I.F.; Lewis, W.;2016, Blake, Collison, D.; McInnes, 7. Pointillart, F.; Guizouarn, T.; Lefeuvre, S.; Golhen, S.; Cador, O.; Ouahab, L. Rational design of a lanthanideke, A.J.; Collison, D.; McInnes, E.J.L.; Winpenny, R.E.P.; et al. A Monometallic Lanthanide Bis(methanediide) Single molecule magnet with based complex featuring Different single-molecule magnets. Chem. Eur. J. 2015, 21, 16929–16934. Single molecule magnet with


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