The syntheses and structures of the phenyl-di-μ

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The syntheses and structures of the phenyl-di-p-methylene-dirhodium complexes, [{(115-C5Me5)Rh(p-

Zhi-Qiang Wang, Harry Adams, Neil A. Bailey, Michael L. Turner, and Peter M. Maitlis

Abstract: Reaction of PhMgBr with [ { ( r 1 5 - ~ S ~ e 5 ) ~ h ( p , - ~ ~ 2in) ,a( halide-specific ~r)2] reaction gave, first, the monophenyl complex 2a [{(r15-~S~e5)~h(p-~~,)]2(~h)(~r)] and then the diphenyl complex 3 [{(-qSC5Mes)Rh(p-CH,)],(Ph),]. X-ray crystal structure determinations showed both molecules to have trans structures, [{(rlS-~5~e5)~h(p,-~~2)),(~h)(~r)] (a = 10.066(3),b = 11.065(3), c = 14.002(3).A; a = 85.23(2)", p = 70.10(2)0,y = 65.22(2)'; U = 1328.2(6) .A3; Z = 2; space group P i , final R, 0.0586) and [{(CSMes)Rh(pCH,)],(Ph),] (a = 17.102(8),b = 10.396(4),c = 16.134(7).A; U = 2869(2) .A3; Z= 4; space group Pccn (D::,NO. 56), final R = 0.0426). Key words : X-ray structure determination, pentamethylcyclopentadienyl, di-p,-methylene, rhodium RCsumC : La rtaction du PhMgBr avec le [{(r15-~s~es)~h(p-~H2)]2(Br)2], dans une rCaction B halogtnure sptcifique, conduit premitrement au complexe monophtnylC 2a [{(q5-~5~e5)~h(p-~~2)](Ph)(Br)] et ensuite au complexe diphtnylt 3 [{(r15-~5~e5)~h(p-~~,)](~h)2]. Des Ctudes par diffraction des rayons X ont perrnis de montrer que les deux moltcules posstdent des structures trans. Pour le [{(r15-~5~es)~h(p,-~~2)](~h)(~r)]. a = 10,066(3),b = 11,065(3)et c= 14,002(3)A, a = 85,23(2)," P = 70,10(2)Oet y = 65,22(2)", U = 1328,2(6).A3, Z = 2, groupe d'espace PT et valeur finale de R = 0,0586 alors que pour le [{(r15-~5~e5)~h(p,-~~2)](~h)2], a= 17,102(8),b = 10,396(4) et c = 16,134(7) .A, U = 2689(2) .A3, Z = 4, groupe d'espace Pccn (D::,NO. 56) et valeur finale de R = 0,0426. Mots c l b : determination de structure, diffraction des rayons X, pentamCthylcyclopentadiCnyle, di-p-rntthyltne, rhodium. [Traduit par la rtdaction]

Introduction W e have previously reported extensive explorations of the chemistry of the di-k-methylene-bis(pentamethylcyclopentadienylrhodium) complexes and have shown that the ((q5C5Me5Rh)(k-CH2)}, unit is unexpectedly stable, despite formally containing Rh(IV) metal centres. This has allowed the synthesis of a large number of substituted species such as [((q5-~5~e5~h)(p-~~2))2(~)(~)] where X, Y are anionic (e.g., halide or pseudo-halide (1-3), alkyl(4), ally1 (3,benzyl Received November l I, 1994. This paper is dedicated to Professor William A.G. Graham on the occasion of his 65th birthday, and in recognition of hisjine and innovative organometnllic chemistry.

Z.-Q. Wang, H. Adams, N.A. Bailey, M.L. Turner, and P.M. ~ a i t l i s . Department ' of Chemistry, The University of Sheffield, Sheffield S3 7HF, England.

'

Author to whom correspondence may be addressed. Telephone: -44- 1 14-2824480.Fax: -44- 1 14-2738673.E-mail: [email protected]

Can. J. Chem. 73:1206-1212 (1995).Printed in Canada / Imprimt au Canada

(6), vinyl (7), carbonate (8), etc.) or neutral ligands (e.g., MeCN, py, C O (9), etc.). For the neutral ligands, the complexes are of course ionic and bear positive charges. The introduction of phenyl has, however, proved quite elusive until now, and neither the mono- nor the diphenyl complex had been efficiently obtained by standard routes. For ,)}2~1 example, reactions of [ ( ( q 5 - ~ 5 ~ e 5 ~ h ) ( ~ - ~ ~with phenyllithium in solvents such as toluene, tetrahydrofuran, ether, or hexane were largely unsuccessful, and only a very small amount ( 20(1)) R indices (all data) Largest diff. peak and hole

C2,H,,BrRh2 66 1.32 293(2) K 0.71073 A Teclinic P1 n = 10.066(3) A a = 85.23(2)" b = 1 1.065(3) 0 = 70.1O(2)" c = 14.002(3) A y = 65.22(2)" 1328.2(6) A3 2 1.654 Mg m-, 2.760 mm-' 664 0.8 x 0.4 x 0.3 mm 3.50 to 45.00' -1 < h < 1 0 , - 1 1 I k 5 1 1 , - 1 4 5 1 5 15 4302 3455 (R,,, = 0.0183) Full-matrix least squares on F' 3455/0/280 1.044 R 1 = 0.0586, wR2 = 0.1556 R1 = 0.0599, wR2 = 0.1572 1.989 and -2.616 e A"

but are quite close to perpendicular (85"-95"); thus the coordination about the metal atoms with respect to the two CH2's and the R or X ligand is reasonably thought of as fac-octahedral. The Rh-R bond lengths in the three complexes [{(C5Me5)Rh(p-CH2)]2Rz].R = Me. 2.1 18 av.(16) A (4); R = Ph, 2.039(6), and R = CH=CH,, 2.001(6) A (7) probably reflect the different hybridizations at the carbon (and hence their different sizes), and differential n-bonding to the metal. The two phenyl groups and the two r 1 5 - ~ , ~ rings e , in complex 3 are tmns to each other; this arrangement is also retained in solution, as shown by the 'H NMR spectra of the methylenic hydrogens. In addition to synthesizing the phenyl complexes 2a and 3, we have also made the mono-p-tolyl and the monop-fluorophenyl complexes 2b and 2c, by the same route and in similar yield to that for 2a. The 'H NMR spectra in the p-CH, region again indicate that all the complexes have the same, tmns, structure in solution. It is interesting that there is no indication of any dynamic behaviour (or isomerization to a cis isomer) in the NMR spectra of any of the complexes 2a-c even in acetone-d6 down to -40°C. This contrasts with the situation in the related methylchloro complex, [{($C,Me5)Rh(p-CH,)),(Me)(Cl)],which is static in C6D6 but shows isomerization and dynamic behaviour in even slightly more polar solvents (1 1).

determinations showed both molecules to have trans structures. There are no obvious structural features that suggest why previous attempts to make phenyl complexes of this series failed, but the success of the Grignard reaction here does appear to depend on the exclusive use of bromides.

Experimental 'H NMR and 13cNMR spectra were measured on a Bruker AM-250 spectrometer using the solvent as internal standard, and IR spectra on a Perkin-Elmer 1710 FT spectrometer. Elemental analyses were performed by the Sheffield University Microanalysis Service. FAB-MS spectra were recorded on a Fisons-VG ProSpec 3000 spectrometer. All reactions were carried out under nitrogen in Schlenk tubes. Solvents were dried and distilled immediately prior to use. Phenylmagnesium bromide, p-fluorophenylmagnesium bromide, and p-tolylmagnesium bromide were purchased from Aldrich; [{(C5Me5)Rh(p-CH2))2Me2],[{(C,Me,)Rh(pCH2)),Br2], and [{(C5Me5)Rh(p-CH2)],C1,] were prepared according to published procedures (1-9).

[{(q5-~5~e5)~h(~-~H2)12(C6H5)Brl (k)

Phenylmagnesium bromide in ether (3.0 M; 0.1 mL, 0.3 mmol) was added dropwise over 10 min by syringe to a deep red solution of [{(C5Me5)Rh(p-CH2)),Br,] (66.4 mg, Conclusion 0.1 mmol) in freshly distilled toluene, and was cooled to The di-p-methylene-dirhodium complex [ { ( r 1 5 - ~ 5 ~ e 5 ) ~ h ( p --40°C. The solution was allowed to warm slowly from CH,)](Br),] undergoes a halide-specific reaction with -40°C to -10°C over 4 h; it was then quenched with satuPhMgBr that gives, first, the monophenyl complex 2a [{($rated aqueous NH,Br (100 kL), and filtered. The filtrate was C,Me5)Rh(p-CH,)],(Ph)(Br)] and then the diphenyl complex evaporated to dryness, and the resulting brown-red solid was 3 [{(r15-~5~e5)~h(p-~~,)]2(~h)2]. X-ray crystal structure extracted with pentane (3 x 50 mL) and the extract filtered and

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Can. J. Chern. Vol. 73, 1995

evaporated to afford 53 mg (86%) of analytically pure 2a after recrystallization from hexane. 'H NMR (CDC13) 6: 1.27 and 1.56 (2 x C,Me5), 7.05 (dt, 2H, o-Ph), 6.86 (tt, 2H, m-Ph), 6.72 (tt, IH, p-Ph); 9.28 (ddd, 2H, J(Rh-H) 4.5; J(H-H) 2 HZ, CH,), 10.26 (ddd, 2H, J(Rh-H) 5; J(H-H) 2Hz, k-CH,). C NMR 6: 9.3 and 10.2 (2 x C5Me5),103.6 (s) and 101.4 (d, J 5 Hz, C5Me5), 156.4 (d, J(Rh-C) 41 Hz, i-Ph), 138.2 (s, o-Ph), 121.9 (s, m-Ph), 127.3 (s, p-Ph), 178.6 (dd, J(Rh-C) 30 Hz, CH,). Anal. calcd. for C,,H,,BrRh,: C 50.85, H 5.9, Br 12.1%, MW 661; found: C 50.8, H 5.8, Br 12.05%, MS, FAB+: m/e 66 1 (M+, 10%). Crystals of 2a were grown from diethyl ether as red blocks; crystal dimensions 0.80 x 0.40 x 0.30 mm; the crystallographic data are summarized in Table 3. Crystal data for C,,H,,BrRh,: M = 661.32. Triclinic, a = 10.066(3), b = 11.065(3), c = 14.002(3) A, a = 85.23(2)", P = 70.10(2)", y = 65.22(2)", U = 1328.2(6) A3, Z = 2, Dc = 1.654 g cm-,, space group p i (c,' , No. 2), Mo-K, radiation (X = 0.71073 A), ~(Mo-K,) = 27.60 cm-', F(000) = 664. Three-dimensional, room temperature X-ray data were collected in the range 3.5 < 20 < 45" on a Siemens P4 diffractometer by the w scan method. The 3239 independent reflections (of 4302 measured) for which IFlIu(lFI) > 4.0 were corrected for Lorentz and polarization effects, but not for absorption. The structure was solved by direct methods and refined by full-matrix least squares on F,. Hydrogen atoms were included in calculated positions and refined in riding mode. Refinement converged at a final R = 0.0586 (wR, = 0.1572 for all 4302 unique data, 280 parameters, mean and maximum 6lu 0.000, 0.000), with allowance for the thermal anisotropy of all non-hydrogen atoms. Minimum and maximum final electron density -2.62 and 1.99 e k3.A weighting scheme w = ll[u2(F2) + (0.1313*~),+ 1.29*P] where P = (FO2+ 2*Fc2)/3was used in the latter stages of refinement. Complex scattering factors were taken from the program package SHELXL 93 (12) as implemented on the Viglen 486dx computer. Selected bond lengths and angles, crystallographic parameters, and fractional atomic coordinates are in Tables 1,3, and 4 respectively; further details, tables of bond lengths and angles, thermal parameters, and atomic coordinates have been deposited as supplementary material.,

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'P-

[{(r15-cs~es)~h(k-c~2)),(4-c~3c6~4)~r~ (2b) This was obtained in 82% yield from [{(C5Me5)Rh(kCH,)),Br,] and 4-tolylmagnesium bromide in ether (1 M, 0.15 mL, 0.15 mmol) by the method used for 2a. 'H NMR (CDC13) 6: 1.26 (s, 15H, C5Me5),1.53 (s, 15H, C5Me5);6.64 (d, 2H; J 8 Hz, 2H-To), 6.84 (d, 2H, J 8 Hz, 3H-To), 2.1 1 (s, 3H, Me), 9.20 (bs, 2H, CH,), 10.18 (dd, 2H, CH,, J(Rh-H) 5 Hz, J(HH) 2.0 Hz). I3cNMR 6: 9.3 (s, C5Me5), 10.2 (s, C5Me5),20.45 (s, Me), 103.5 (s, C5Me5), 101.4 (d, C5Me5,J 5 Hz), 137.8 (s, -

These data can be purchased from: The Depository of Unpublished Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, Canada KIA 052. Bond lengths and angles and hydrogen atom coordinates have also been deposited at the Cambridge Crystallographic Data Centre and can be obtained on request from The Director, Cambridge Crystallographic Data Centre, University Chemical Laboratory, 12 Union Road, Cambridge CB2 IEZ, UK. Structure factors are no longer being deposited and can be obtained on request from the author.

Table 4. Atom coordinates (x lo4) and equivalent isotropic displacement parameters (A' x 10') for complex 2a,

[((C5Me,)Rh(~-CH2)j2(Ph)(Br)]. U(eq) is defined as one third of the trace of the orthogonalized Uji tensor. Atom

x

Y

z

U(eq)

2-TO), 128.3 (s, 4-TO), 126.8 (s, 3-TO), 178.6 (dd, CH,, J(RhC) 30 Hz). Anal. calcd. for C2,H4,BrRh2: C 51.6, H 6.1, Br 11.8%, M 675; found: C 5 1.4, H 5.8, Br 11.75%, MS, FAB+: m/e 675 (M+, 20%).

[ { ( r 1 5 - ~ s ~ e 5 ) ~ h ( ~ - ~ ~ 2 > ) 2 ( 4 -(~2~~6)~ 4 ) ~ r l This was obtained in 82% yield from [{(C5Me5)Rh(pCH,)),Br,] and 4-fluorophenylmagnesium bromide in ether (1 M, 0.15 mL, 0.15 mmol) by the method used for 2a. 'H NMR (CDC1,) 6: 1.32 (s, 15H, C5Me5), 1.57 (s, 15H, C5Me5), 6.64 (dtd, 2H, 2H-C6H,F, J 8 and 2 Hz), 6.96 (dtd, 2H, 3HC6H4F,J 8 and 2 Hz), 9.24 (bs, 2H, k-CH,), 10.18 (dd, p CH,, J(Rh-H) 4 Hz; J(H-H) 1 Hz). 13cNMR 6 : 9.37 (s, Me), 10.18 (s, Me), 103.7 (s, C5Me5), 101.4 (d, C5Me5,J(Rh-C) 5 Hz), 115.7 (d, J(C-F) 22 Hz), 138.2(s), 128.6(s). Anal. calcd. for C,,H,,BrFRh,: C 49.5, H 5.6%, M 678; found: C 49.4, H 5.7%, MS, FAB': m/e 678 (M+,25%). [ { ( r l 5 - ~ 5 ~ e S > ~ h ( ~ - ~ ~ 2(3) )I2ph2l Phenylmagnesium bromide in ether (3.0 M; 0.12 mL, 0.36 mmol) was added dropwise by syringe over 10 min to a deep red solution of [{(C5Me5)Rh(p-CH2)),Br2](66.4 mg,

Wang et al. Table 5. Crystal data and structure refinement for complex 3, [((C,Me,)Rh(pCHJ lz(ph)zl.

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Empirical formula Formula weight Temperature Wavelength Crystal system Space group Unit cell dimensions

Volume

z

Density (calculated) Absorption coefficient F(OO0) Crystal size 0 range for data collection Index ranges Reflections collected Independent reflections Absorption correction Max. and min. transmission Refinement method Datalrestraintslpararneters Goodness-of-fit on F2 Final R indices [I > 2o(I)] R indices (all data) Largest diff. peak and hole

C,'HJ,Rh2 658.5 1 293(2) K 0.71073 A Orthorhombic Pccn a = 17.102(8) A a = 90" 0 = 10.396(4) A P = 90" c = 16.134(7) A = 90" 2869(2) A3 4 1.525 Mg m-' 1.171 mm-' 1352 0.7 x 0.45 x 0.3 mm 2.29 to 22.48" -15h118,-15k~ll,-151117 2567 1877 (R,,, = 0.0244) Semi-empirical 0.355 and 0.294 Full-matrix least squares on F2 1 877101163 1.078 R1 = 0.0426, wR2 = 0.1 178 R1 = 0.0521, wR2 = 0.1235 0.674 and -0.555 e A" -

0.1 mmol) in freshly distilled toluene (10 mL) cooled to -40°C. The reaction mixture was stirred at this temperature, and was allowed to warm slowly to - 10°C over 2 h; it was finally allowed to warm to room temperature, where it was stirred for 6 h. The mixture was then quenched with saturated aqueous NH,Br (100 FL), filtered, and the filtered solution quickly passed through a short Florisil column, eluting with toluene. Removal of the toluene in vacuo left a red solid, which was extracted with pentane (15 mL); removal of the pentane left 34 mg (52%) of analytically pure [( (C,Me,)Rh(k-CH2)),Ph,]. 'H NMR (CD2C12) 6: 1.12 (s, 30H, C,Mes), 8.90 (t, k-CH,, 4H, J(Rh-H) 1.5 Hz), 7.0 (dt, 4H, J 7 Hz, 1.5 Hz), 6.76 (dt, 4H, J 7 Hz, 1.5 Hz), 6.68 (dt, 2H, J 7 Hz, 1.5 Hz). 13cNMR (CD2Cl,) 6: 9.37 (s, C,Me,), 102.4 (s, C,Me,), 121.7(s), 126.9(s), 139.4 (s), 156.6 (dd, J 4 3 and 10 Hz), 174.2 (t, CH,, J(Rh-C) 29 Hz). Anal. calcd. for C3,H,Rh2: C 62.0, H 6.7, M 658; found: 61.9, 6.8%, FABMS: 658 (MC, 100%). Deep red oblong crystals of 3 were grown from pentanemethanol, the crystallographic data are summarized in Table 5. Crystal data for C3,H4,Rh2: M = 658.5 1; crystal dimensions 0.70 x 0.45 x 0.3 mm. Orthorhombic, a = 17.102(8), b = 10.396(4), c = 16.134(7) A, U = 2869(2) A3, Z = 4, Dc = 1.525 g ~ m - space ~, roup Pccn (D!& NO. 56), Mo-K, radiation = 0.71073 ), ~(Mo-KCL) = l . 171 mm-l, F(000) = 1352. Three-dimensional, room temperature X-ray data were collected in the range 3.5 < 28 < 45" on a Siemens P4 diffractometer by the w scan method. The 1518 independent reflections (of 2567 measured) for which IFlIa(lFI) > 4.0 were corrected for Lorentz and polarization effects, and for absorp-

(x

-

Table 6. Atom coordinates (x 10') and equivalent isotropic displacement parameters (A2 x lo3) for complex 3, [((C,Me,)Rh(p-CH2)J2(Ph),]. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor

f

tion by analysis of 10 azimuthal scans (minimum and maximum transmission coefficients 0.294 and 0.355). The structure was solved by direct methods and refined by fullmatrix least squares on F,. Hydrogen atoms were included in

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calculated positions and refined in riding mode. Refinement converged at a final R = 0.0426 (wR, = 0.1235, for all 1877 data, 163 parameters, mean and maximum 6/u 0.000, 0.001), with allowance for the thermal anisotropy of all non-hydrogen atoms. Minimum and maximum final electron density -Oi555 and 0.674 e A - ~ .A weighting scheme w = ll[u2(~[) + ( 0 . 0 7 0 8 * ~+ ) ~4.53*P] where P = (F,' + 2 * ~ , ~ ) was / 3 used in the latter stages of refinement. Complex scattering factors were taken from the program package SHELXL 93 (12) as implemented on the Viglen 486dx computer. Selected bond lengths and angles, crystallographic parameters, and fractional atomic coordinates are in Tables 2, 5, and 6, respectively; further details, tables of bond lengths and angles, thermal parameters, and atomic coordinates have been deposited.,

Acknowledgements We thank the Royal Society, the Science and Engineering Research Council, and the EU Human Capital and Mobility scheme (contract no: ERBCHRXCT930147) for support.

References 1. K. Isobe, P.M. Bailey, P. Schofield, J.T. Gauntlett, A. Nutton, and P.M. Maitlis. J. Chem. Soc. Chem. Commun. 425 (1982).

Can. J. Chem. Vol. 73, 1995 2. J. Martinez, J.B. Gill, H. Adams, N.A. Bailey, I.M. Saez, and P.M. Maitlis. Can. J. Chem. 67, 1698 (1989). 3. J. Martinez, H. Adams, N.A. Bailey, and P.M. Maitlis. J. Oganomet. Chem. 405,393 (199 1 ). 4. K. Isobe, A. Vbquez de Miguel, P.M. Bailey, S. Okeya, and P.M. Maitlis. J. Chem. Soc. Dalton Trans. 1441 (1983). 5. B.E. Mann, N.J. Meanwell, C.M. Spencer, B.F. Taylor, andP.M. Maitlis. J. Chern. Soc. Dalton Trans. 1555 (1985). 6. N.J. Meanwell, A.J. Smith, and P.M. Maitlis. J. Chem. Soc. Dalton Trans. 1419 (1986). 7. J. Martinez, J.B. Gill, H. Adams, N.A. Bailey, I.M. Saez, G.J. Sunley, and P.M. Maitlis. J. Organomet. Chem. 394,583 (1990). 8. N.J. Meanwell, A.J. Smith, H. Adams, S. Okeya, and P.M. Maitlis. Organometallics, 2, 1705 (1983). 9. K. Isobe, S. Okeya, N.J. Meanwell, A.J. Smith, H. Adams, and P.M. Maitlis. J. Chem. Soc. Dalton Trans. 1215 (1984). 10. W.D. Jones and V.L. Kuykendall. Inorg. Chem. 30, 2615 (1991). 11. S. Okeya, N.J. Meanwell, B.F. Taylor, K. Isobe, A. Vazquez de Miguel, and P.M. Maitlis. J. Chem. Soc. Dalton Trans. 1453 (1984). 12. G.M. Sheldrick. SHEIXL 93, an integrated system for solving and refining crystal structures from diffraction data (Revision 5.1). University of Gottingen, Germany. 1993.