Synthesis, crystal structure and catalytic property of a

Inorganic Chemistry Communications 40 (2014) 35–38

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Synthesis, crystal structure and catalytic property of a samarium complex with Hpytza [Hpytza = 5-(3-pyridyl) tetrazole-2-acetic acid] Dian-Yu Chen, Jian-Hua Zou, Wu-Xiang Li, Bo Xu, Qiao-Yun Li ⁎, Gao-Wen Yang ⁎, Juan Wang, Ya-Mei Ding, Ying Zhang, Xiao-Feng Shen Jiangsu Key Laboratory of Advanced Functional Materials, Department of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500, PR China

a r t i c l e

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Article history: Received 20 October 2013 Accepted 13 November 2013 Available online 19 November 2013 Keywords: Sm(III) Hpytza Crystal structure Catalytic polymerization

a b s t r a c t A reaction of SmCl3·6H2O and Hpytza (Hpytza = 5-(3-pyridyl) tetrazole-2-acetic acid) under the presence of KOH, produced a novel coordination compound, [Sm(pytza)2Cl(H2O)2] (1). This compound was structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compound 1 reveals an 1D structure via its bridging pytza ligand and simultaneously shows a specific and good catalytic behavior for the photo-polymerization of vinyl monomers. Furthermore, the high molecular weight polymers with narrow polydispersity were obtained, and the polymerization showed controlled characteristics. The catalyst can be isolated from polymer products easily and reused for at least 10 times. © 2013 Published by Elsevier B.V.

In recent years, great emphasis has been attached to organic lanthanide complexes for their application as coordination polymerization catalysts or catalyst precursors [1,2]. A variety of lanthanide derivatives, such as alkoxide [3], amide [4], amidinate and guanidinate [5], monocyclopentadienyl metallocenes [6], borohydride [3(b), 7], bis(phosphinimino)methanide [8], cyclooctatetraene [7(a), 9], and trialkylsilylene [10] complexes have been reported. In our previous work, we have reported the synthesis, characterization and properties of some coordination compounds based on N-heterocyclic carboxylic acid ligands, such as [3-(2-pyridyl)-1-pyrazolyl] acetic acid, 5-[N-acetato(4-pyridyl)]tetrazolate, 1H-tetrazolate-5-acetic acid, and so on [11], where the most interesting results are found for the initiating polymerization capacity of lanthanide derivative with 1H-tetrazolate5-acetic acid ligand [11(i), 11(j)]. Encouraged by the facts above, today we choose another new N-heterocyclic carboxylic acid ligand, 5-(3-pyridyl)tetrazole-2-acetic acid (Hpytza) to construct novel coordination compounds with samarium and we have successfully synthesized [Sm(pytza)2Cl(H2O)2] (1), to our delight. Here, we describe the synthesis and structure of 1, and its catalytic activity in the photopolymerization of vinyl monomers, which has not been reported before, to the best of our knowledge. Compound 1 was obtained by treatment of Hpytza with SmCl3·6H2O under hydrothermal condition [12]. The structure of 1 is identified by elemental analysis, IR and single crystal X-ray diffraction [13]. The

⁎ Corresponding authors. Tel.: +86 13915618328; fax: +86 52251842. E-mail addresses: [email protected] (Q.-Y. Li), [email protected] (G.-W. Yang). 1387-7003/$ – see front matter © 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.inoche.2013.11.004

single crystal X-ray analysis reveals that compound 1 displays a one dimensional structure with monoclinic space group C2/c. As shown in Fig. 1, each Sm(III) center is nine-coordinated by six O atoms from four pytza ligands and two O atoms from two coordinated water molecules and a Cl anion, forming a distorted monocapped square antiprism coordination geometry. The pytza ligand chelates one Sm(III) ion via two carboxylate O atoms while simultaneously binds to a second Sm(III) ion via one carboxylate O atom, thereby generating an 1D chain structure extending along the c axis with neighboring Sm⋯Sm distance of 4.123 Å and the Sm⋯Sm⋯Sm bite angle of 147.30° (Fig. 2). Within the one-dimensional chain, one hydrogen-bond interaction is formed between the coordinated water molecule and Cl anion [O(3)⋯Cl(1) 3.096 Å/173°]. The adjacent 1D chains of 1 are held together through one hydrogen-bond interaction between the water molecule and N atom of the pyridine ring [O(3)⋯N(5)2.740 Å/172°], to generate a three dimensional network (Fig. 3). The weak coordination of hard-base hetero atom to the lanthanide based center is well-known to be the cause for their catalytic behavior in vinyl monomer polymerization [14, 11(i)]. Therefore, compound 1 is firstly used as photo-catalysts for mediating photo-polymerization of methyl methacrylate (Table 1), a sample of vinyl monomers [15]. Compound 1 did have the capacity to initiate methyl methacrylate polymerization under UV light radiation to give relatively high molecular weight polymers with narrow polydispersity, however, in blank case no polymer is obtained. This is a fast and smooth reaction; the acceleration in rate is manifested by a lowering of molecular weight from 3.60 × 104 to 0.49 × 104, and broadening of the polydispersity from 1.39 to 2.79, which is ascribed to the chain transfer reaction [16]. These observations made us to lower the radiation power and temperature in order to avoid excessive chain transfer reaction. Polymerization

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Fig. 1. The coordination environment of Sm(III) atom in 1. Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (°): Sm(1)\O(3)2.4005(16);Sm(1)\O(1A) 2.4600(17); Sm(1)\O(2) 2.4571(18); Sm(1)\O(1)2.8333(18); Sm(1)\Cl(1)2.7288(10); O(3)\Sm(1)\O(3B)68.05(8); O(3)\Sm(1)\O(2)76.83(6); O(3B)\Sm(1)\O(2) 93.07(6); O(2)\Sm(1)\O(2B)167.93(8); O(3)\Sm(1)\O(1A)129.25(6); O(3B)\ Sm(1)\O(1A)73.13(6);O(2)\Sm(1)\O(1A)73.89(6); O(2B)\Sm(1)\O(1A)108.72(6); O(1A)\Sm(1)\O(1C)156.15(8); O(3)\Sm(1)\Cl(1)145.98(4); O(2)\Sm(1)\Cl(1) 96.04(4); O(1A)\Sm(1)\Cl(1)78.07(4); O(3)\Sm(1)\O(1B)130.87(5); O(2)\Sm(1)\ O(1B)135.18(5); O(1A)\Sm(1)\O(1B)61.33(6); O(1C)\Sm(1)\O(1B)112.84(5); Cl(1)\Sm(1)\O(1B)77.20(4); O(3)\Sm(1)\O(1)73.32(5); O(3B)\Sm(1)\O(1) 130.87(5); O(2)\Sm(1)\O(1)48.49(5); O(1B)\Sm(1)\O(1)154.39(7).

proceeds efficiently at reaction 4 reaching 94% conversion at 20 °C and 300 W power. When the molar ratio of monomer to complex 1 is doubled from 50 to 100, an approximate doubling of the Mn is observed (entries 4 and 7, Table 1), which is expected for a controlling polymerization. Methyl methacrylate, styrene, vinyl acetate, vinyl iso-butyl ether, and butyl acrylate are used as representatives of the vinyl monomers, to investigate the catalytic lives of compound 1 (entries 4, 8, 9, 10, and 11, Table 1). All reactions at 20 °C and 300 W process fast and smoothly. This takes together with the relatively narrow PDI values and high Mn of the products, indicating that the polymerization shows controlled characteristics. Fig. 4 shows the evolution of the Mn as a function of [M]/[I] for reactions 4, 8, 9, 10, and 11, which increases linearly again, corresponding to the expected results for controlling polymerization. Compound 1 is immiscible with acetone, which leads to the easy isolation of the catalyst from the polymer solution for potential reuse. After 10 cycle reuse in methyl methacrylate polymerization (see Fig. 5), catalyst recovery is up to 92.4%, molecular weight and polydispersity of polymers retain a stable level (Mn is changed randomly between 31,532 and 37,687, PDI is changed at random between 1.16 and 1.43), which indicate that compound 1 is a recovery catalyst and can repeat at least 10 times. In summary, a novel 1D chain samarium(III) coordination polymer containing the pytza ligand was firstly prepared. This complex shows a specific and good catalytic behavior in the photopolymerization of vinyl monomers, and high molecular weight polymers with narrow polydispersity in good yields are obtained. The polymerization mediated by compound 1 shows controlled characteristics. The complex is a recovery catalyst, and can repeat 10 times at least.

Acknowledgment We greatly appreciate the financial support from the College Students' Innovation and Entrepreneurship Training Program of Jiangsu Province (201310333010Z).

Fig. 2. The 1D structure of 1. (a) Along the axis b; and (b) along the axis c. Hydrogen atoms are omitted for clarity.

D.-Y. Chen et al. / Inorganic Chemistry Communications 40 (2014) 35–38

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Fig. 3. The 3D network structure of 1 formed via hydrogen bonding interactions.

Table 1 Final molecular weight and conversion data for the polymers synthesized in this work. Entrya

[Mo]/[I]

Temp (°C)

Power (W)

Conv (%)b

Mn × 10−4c

Mw/Mnc

1 2 3 4 5 6 7 8d 9e 10f 11g

50 50 50 50 50 50 100 50 50 50 50

60 50 40 20 20 20 20 20 20 20 20

300 300 300 300 500 800 300 300 300 300 300

27 43 67 94 73 15 86 84 78 79 88

0.69 1.05 1.71 3.60 0.82 0.49 7.57 1.73 1.37 0.81 0.43

1.73 1.45 1.41 1.39 1.87 2.79 1.41 1.34 1.26 1.19 1.22

a b c d e f g

All reactions carried were 10% g/g in acetone. Conversion from integration of gravimetric method. Determined using PL GPC-50 against polystyrene standards. Styrene. Vinyl acetate. Vinyl iso-butyl ether. Butyl acrylate.

Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.inoche.2013.11.004.

Fig. 4. Evolution of molar mass with [Mo]/[I] for polymerization; line draw is the linear regression fit through the data. (■) Polymerization of methyl methacrylate, (●) polymerization of styrene, (▲) polymerization of vinyl acetate, (▼) polymerization of vinyl iso-butyl ether, and (♦) polymerization of butyl acrylate.

References [1] G. Erker, R. Aul, Chem. Ber. 124 (1991) 1301. [2] H. Yasuda, Prog. Polym. Sci. 25 (2000) 573. [3] (a) C. Qian, D. Zhu, D.J. Li, J. Organomet. Chem. 430 (1992) 175; (b) F. Bonnet, A.R. Cowley, P. Mountford, Inorg. Chem. 44 (2005) 9046; (c) F. Yuan, J. Yang, L. Xiong, J. Organomet. Chem. 691 (2006) 2534; (d) T.V. Mahrova, G.K. Fukin, A.V. Cherkasov, A.A. Trifonov, N. Ajellal, J.-F. Carpentier, Inorg. Chem. 48 (2009) 4258; (e) M.A. Sinenkov, G.K. Fukin, A.V. Cherkasov, N. Ajellal, T. Roisnel, F.M. Kerton, J.-F. Carpentier, A.A. Trifonov, New J. Chem. 35 (2011) 204; (f) H.E. Dyer, S. Huijser, N. Susperregui, F. Bonnet, A.D. Schwarz, R. Duchateau, L. Maron, P. Mountford, Organometallics 29 (2010) 3602. [4] (a) W.A. Herrmann, R. Anwander, F. Munck, W. Scherer, Chem. Ber. 126 (1993) 331; (b) W. Rong, D. Liu, H. Zuo, Y. Pan, Z. Jian, S. Li, D. Cui, Organometallics (2012); (c) X. Shen, M. Xue, R. Jiao, Y. Ma, Y. Zhang, Q. Shen, Organometallics 31 (2012) 6222; (d) Y. Yang, K. Lv, L. Wang, Y. Wang, D. Cui, Chem. Commun. 46 (2010) 6150; (e) P. Jochmann, T.S. Dols, T.P. Spaniol, L. Perrin, L. Maron, J. Okuda, Angew. Chem. Int. Ed. 49 (2010) 7795; (f) T.V. Mahrova, G.K. Fukin, A.V. Cherkasov, A.A. Trifonov, N. Ajellal, J.-F. Carpentier, Inorg. Chem. 48 (2009) 4258; (g) K. Naktode, R.K. Kottalanka, T.K. Panda, Z. Anorg. Allg. Chem. 639 (2013) 73. [5] (a) G.G. Skvortsov, M.V. Yakovenko, P.M. Castro, G.K. Fukin, A.V. Cherkasov, J.-F. Carpentier, A.A. Trifonov, Eur. J. Inorg. Chem. (2007) 3260; (b) F. Yuan, Y. Zhu, L. Xiong, J. Organomet. Chem. 691 (2006) 3377; (c) G.G. Skvortsov, M.V. Yakovenko, G.K. Fukin, A.V. Cherkasov, A.A. Trifonov, Russ. Chem. Bull. 56 (2007) 1742; (d) J. Kratsch, M. Kuzdrowska, M. Schmid, N. Kazeminejad, C. Kaub, P. Oña-Burgos, S.M. Guillaume, P.W. Roesky, Organometallics 32 (2013) 1230; (e) M.V. Yakovenko, A.A. Trifonov, E. Kirillov, T. Roisnel, J.-F. Carpentier, Inorg. Chim. Acta 383 (2012) 137. [6] (a) I. Palard, A. Soum, S.M. Guillaume, Chem. Eur. J. 10 (2004) 4054; (b) M. Visseaux, T. Chenal, P. Roussel, A. Mortreux, J. Organomet. Chem. 691 (2006) 86; (c) S. Demir, N.A. Siladke, J.W. Ziller, W.J. Evans, Dalton Trans. 41 (2012) 9659;

Fig. 5. The recovery results of the catalyst. (■) Mn and (○) PDI.

38

[7]

[8]

[9] [10] [11]

D.-Y. Chen et al. / Inorganic Chemistry Communications 40 (2014) 35–38 (d) G. Cortial, X.-F. Le Goff, M. Bousquie, C. Boisson, P. Le Floch, F. Nief, J. Thuilliez, New J. Chem. 34 (2010) 2290. (a) S.M. Cendrowski-Guillaume, G. Le Gland, M. Nierlich, M. Ephritikhine, Organometallics 19 (2000) 5654; (b) P. Zinck, A. Valente, A. Mortreux, M. Visseaux, Polymer 48 (2007) 4609; (c) F. Bonnet, C.D.C. Violante, P. Roussel, A. Mortreux, M. Visseaux, Chem. Commun. (2009) 3380; (d) M. Visseaux, M. Terrier, A. Mortreux, P. Roussel, C. R. Chim. 10 (2007) 1195; (e) D. Barbier-Baudry, O. Blacque, A. Hafid, A. Nyassi, H. Sitzmann, M. Visseaux, Eur. J. Inorg. Chem. (2000) 2333; (f) Z. Jian, W. Zhao, X. Liu, X. Chen, T. Tang, D. Cui, Dalton Trans. 39 (2010) 6871; (g) F. Bonnet, C.E. Jones, S. Semlali, M. Bria, P. Roussel, M. Visseaux, P.L. Arnold, Dalton Trans. 42 (2013) 790. (a) J. Jenter, P.W. Roesky, N. Ajellal, S.M. Guillaume, N. Susperregui, L. Maron, Chem.–Eur. J. 16 (2010) 4629; (b) J. Jenter, G. Eickerling, P.W. Roesky, J. Organomet. Chem. 695 (2010) 2756; (c) S.M. Guillaume, P. Brignou, N. Susperregui, L. Maron, M. Kuzdrowska, P.W. Roesky, Polym. Chem. (2011) 1728. S. Cendrowski-Guillaume, M. Nierlich, M. Lance, M. Ephritikhine, Organometallics 17 (1998) 786. M.F. Lappert, A. Singh, Inorg. Synth. 27 (1990) 168. (a) G.W. Yang, Q.Y. Li, Y. Zhou, G.Q. Gu, Y.S. Ma, R.X. Yuan, Inorg. Chim. Acta 362 (2009) 1234; (b) Y. Zhou, G.W. Yang, Q.Y. Li, K. Liu, G.Q. Gu, Y.S. Ma, R.X. Yuan, Inorg. Chim. Acta 362 (2009) 1723; (c) Q.Y. Li, G.W. Yang, Y.S. Ma, M.J. Li, Y. Zhou, Inorg. Chem. Commun. 11 (2008) 795; (d) L. Shen, J. Yang, G.W. Yang, Q.Y. Li, X.Y. Tang, F. Zhou, Z.F. Miao, J.N. Jin, W. Shen, Inorg. Chim. Acta 370 (2011) 150; (e) G.W. Yang, Q.Y. Li, Y. Zhou, G.Q. Gu, Y.S. Ma, R.X. Yuan, Inorg. Chem. Commun. 11 (2008) 1239; (f) G.W. Yang, Q.Y. Li, Y. Zhou, P. Sha, Y.S. Ma, R.X. Yuan, Inorg. Chem. Commun. 11 (2008) 723; (g) J. Yang, L. Shen, G.W. Yang, Q.Y. Li, W. Shen, J.N. Jin, J.J. Zhao, J. Dai, J. Solid State Chem. 186 (2012) 124; (h) Q.Y. Li, F. Zhou, C. Zhai, L. Shen, X.Y. Tang, J. Yang, G.W. Yang, Z.F. Miao, J.N. Jin, W. Shen, Inorg. Chem. Commun. 14 (2011) 843; (i) Q.Y. Li, D.Y. Chen, M.H. He, G.W. Yang, L. Shen, C. Zhai, W. Shen, K. Gu, J.J. Zhao, J. Solid State Chem. 190 (2012) 196;

[12]

[13]

[14] [15]

[16]

(j) G.W. Yang, D.Y. Chen, C. Zhai, X.Y. Tang, Q.Y. Li, F. Zhou, Z.F. Miao, J.N. Jin, H.D. Ding, Inorg. Chem. Commun. 14 (2011) 913. Synthesis of 1: Hpytza (0.0410 g, 0.2 mmol) was dissolved in distilled water (2 mL), and the pH value of the solution was adjusted to 6 with KOH (0.2 mol/L). Then ethanol (3 mL) and SmCl3·6H2O (0.0365 g, 0.1 mmol) were added to this solution. The mixture was sealed in a 25 mL Teflon lined stainless steel container, which was heated at 120 °C for 48 h and then cooled to room temperature. The crystals of 1 were obtained. Anal. Calcd for C16H16ClN10O6Sm: C, 30.49; H, 2.56; N, 22.23%. Found: C, 30.38; H, 2.52; N, 22.31%. IR (KBr, cm−1): 3347(s), 1612(s), 1569(s), 1473(w), 1447(s), 1419(s), 1394(w), 1377(m), 1316(m), 1196(m), 1038 (m), 826(m), 704(s), 637(m), 580(m). Crystal data for 1: C16H16ClN10O6Sm, Mr = 630.20, monoclinic, space group C2/c, a = 23.536(5) Å, b = 11.244(2) Å, c = 8.8264(18) Å, β = 107.59(3), V = 2226.6(8) Å3, Z = 4, T = 291 K, Dcalcd = 1.880 g·cm−3, μ = 2.814 mm−1, R (wR) = 0.0197 (0.0483) and GOF = 1.138 for 2454 reflections with I N 2.00σ(I). The crystal structures of 1 were solved by direct methods using SHELXS-97 program and refined on F2 by full-matrix least squares using SHELXL-97 program. All non-H atoms were refined anisotropically while all H atoms were placed in geometrically idealized positions. E.Y.X. Chen, Chem. Rev. 109 (2009) 5157. Typical polymerization process: Compound 1 of 0.063 g (0.1 mmol) was mixed with 10 g of acetone in a quartz reaction tube, stirred by magnetic power. The dry nitrogen was input for about 20 min to eliminate the effect of possible air, and then methyl methacrylate of 1.00 g (10 mmol) was added. The polymerization was performed on a XPA-1 photochemical reactor, with 300 W Hg light source and the rolling rate was 20 rpm; the wavelength of the radiation light was selected as 365 nm. The polymerization was terminated by the addition of acidic methanol. The polymer product was precipitated into 50 ml methanol, filtered, washed with methanol, and dried in a vacuum oven at 50 °C overnight to a constant weight. Gel permeation chromatography (GPC) analyses of polymer samples were carried out at 25 °C using THF as eluent on a Polymer Laboratory-50 instrument and calibrated using monodispersed polystyrene standards at a flow rate of 1.0 ml/min. Numberaverage molecular weight and polydispersity of polymers were given relative to PS standards. (1) J.A. Carmichael, D.M. Haddleton, A.F. Stefan, K.R. Seddon, Chem. Commun. 14 (2000) 1237; (2) D.Y. Chen, X.Y. Wang, G.W. Yang, Q.Y. Li, W. Chai, R.X. Yuan, S.F. Liu, F. Gao, H.Y. Jin, S. Roy, J. Mol. Catal. A: Chem. 363 (2012) 195.