Synthesis and Structural Characterization of Heterobimetallic Bismuth

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Organometallics 2009, 28, 5733–5738 DOI: 10.1021/om900623w

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Synthesis and Structural Characterization of Heterobimetallic Bismuth Complexes with Main Group and Transition Metals Bijan Nekoueishahraki, Anukul Jana, Herbert W. Roesky,* Lallan Mishra, Daniel Stern, and Dietmar Stalke Institute of Inorganic Chemistry, University of G€ ottingen, Tammannstrasse 4, 37077 G€ ottingen, Germany Received July 16, 2009

The heterobimetallic bismuth-oxo-bridged complexes containing the Bi-O-M (M = Al, Ga, Ge, Zr, Hf) core were prepared. The reaction of L1BiNMe2 (1) [L1 = 1,8-C10H6(NSiMe3)2] with LM(Me)(OH) and LGe(OH) (M = Al, Ga, L = CH((CMe)NAr)2, Ar = 2,6-iPr2C6H3) proceeds via HNMe2 elimination and provides the complexes L1Bi( μ-O)MMeL (M=Al 2; Ga, 3) and L1Bi( μ-O)GeL (4). The transition metal hydroxides Cp*2ZrMe(OH) and Cp*2HfCl(OH) react with 1 in n-hexane and toluene, respectively, under elimination of 1 equiv of HNMe2 to generate the corresponding complexes L1Bi( μ-O)ZrMeCp*2 (5) and L1Bi( μ-O)HfClCp*2 (6). Compounds 3, 4, and 6 represent the first examples of structurally characterized heterobimetallic complexes featuring the Bi-O-Ga, Bi-O-Ge, and Bi-O-Hf moiety, respectively. The crystal structural data show that the complexes 3 and 4 crystallize in the monoclinic space group P21/c and P21/n, while the complexes 5 and 6 are present in the monoclinic space group Pn. Moreover all compounds have been characterized by element analysis, electron impact mass spectrometry, and NMR spectroscopy. Introduction Since the first isolation and characterization of a bismuth-transition metal heterobimetallic alkoxide in 1996,1 a wide variety of bismuth heterobimetallic complexes have been synthesized and reviewed.2 Recently these complexes have attracted increasing interest due to their potential applications as high Tc superconductors,3 in nonlinear optics,4 in oxidation reactions, as catalysts,5 and as thermoelectric and ferroelectric materials. They have also been utilized as precursors in MOCVD for oxide materials6 and in sol-gel synthesis.7 It has been observed that the bismuth germanium oxide system is the best candidate for electrooptic voltage sensors,8 and the mixed oxides of aluminum

and bismuth show high oxide-ion conductivity.9 Limberg and co-workers reported the first structurally characterized molecular complexes with Bi-O-Mo linkages. These moieties are thought to be the active oxo-transfer sites during allylic oxidation of propene.10 The solid-state structure of the first coordination complex containing bismuth and aluminum has also been described.11 When employing discrete, well-defined heterobimetallic compounds as potential single-source precursors, it is important to control the chemical composition and the dimensions of the metal oxide surface of the final material.12 There are several methods available to assemble heterobimetallic complexes including solid-state techniques and wet chemical approaches.13 As part of our ongoing studies with heterobimetallic compounds, we have recently reported the synthesis and structural characterization of μ-oxo-bridged Al-O-M (M = Zr, Ti, Hf), M-O-M1 (M = Ti, Zr; M1 = Al, Ga), GeO-M (M = Zr, Hf), and Al-O-M-O-Al (M = Ti, Zr) complexes.14 Herein we report a general synthetic approach

*To whom correspondence should be addressed. E-mail: hroesky@ gwdg.de. (1) Pell, J. W.; Davis, W. C.; zur Loye, H. C. Inorg. Chem. 1996, 35, 5754–5755. (2) (a) Mehring, M. Coord. Chem. Rev. 2007, 251, 974–1006. (b) Meendoza-Espinosa, D.; Hanna, T. A. Inorg. Chem. 2009, 48, 7452–7456. (c) Knispel, C.; Limberg, C.; Mehring, M. Organometallics 2009, 28, 646– 651. (d) Stavila, V.; Thurston, J. H.; Whitmire, K. H. Inorg. Chem. 2009, 48, 6945–6951. (e) Li, B; Zhang, H.; Huynh, L.; Diverchy, C.; Hermans, S.; Devillers, M; Dikarev, E. V. Inorg. Chem. 2009, 48, 6152–6158. (3) Hodge, P.; James, S. C.; Norman, N. C.; Orpen, A. G. J. Chem. Soc., Dalton Trans. 1998, 4049-4054, and references therein. (4) Parola, S.; Papiernik, R.; Hubert-Pfalzgraf, L. G.; Bois, C. J. Chem. Soc., Dalton Trans. 1998, 737–739. (5) (a) Ono, T.; Ogata, N.; Kuczkowski, R. L. J. Catal. 1998, 175, 185–193. (b) Grasselli, R. K.; Burrington, J. D. Ind. Eng. Chem. Prod. Res. Dev. 1984, 23, 393–394. (6) (a) Doppelt, P. Coord. Chem. Rev. 1998, 178-180, 1785–1809. (b) Marks, T. J. Pure Appl. Chem. 1995, 67, 313–318. (7) (a) Park, Y.; Nagai, M.; Miyayama, M. J. Mater. Sci. 2001, 36, 1261–1269. (b) Kim, Y. T.; Hwang, C.; Chae, H. K.; Lee, Y. K.; Lee, W. I.; Dong, Y. W.; Yun, H. J. Sol-Gel Sci. Technol. 2000, 19, 301–304. (8) (a) Zhang, N.; Ding, Z.; Wu, Y.; Salomon, M. IEEE Trans. Nucl. Sci. 1990, 37, 216–219. (b) Li, C.; Yoshino, T. Appl. Opt. 2002, 41, 5391– 5397.

(9) Lee, C. K.; Bay, B. H.; West, A. R. J. Mater. Chem. 1996, 6, 331– 335. (10) (a) Hunger, M.; Limberg, C.; Kircher, P. Angew. Chem. 1999, 111, 1171–1174. Angew. Chem., Int. Ed. 1999, 38, 1105-1108. (b) Roggan, S.; Limberg, C.; Zimmer, B.; Brandt, M. Angew. Chem. 2004, 116, 2906–2910. Angew. Chem., Int. Ed. 2004, 43, 2846-2849. (11) Thurston, J. H.; Trahan, D.; Ould-Ely, T.; Whitmire, K. H. Inorg. Chem. 2004, 43, 3299–3305. (12) (a) Jones, A. C. J. Mater. Chem. 2002, 12, 2576–2590. (b) Mao, Y.; Park, T.-J.; Wong, S. S. Chem. Commun. 2005, 5721–5735. (13) (a) Gopalakrishnan, J. Chem. Mater. 1995, 7, 1265–1275. (b) Kudo, A.; Omori, K.; Kato, H. J. Am. Chem. Soc. 1999, 121, 11459–11467. (14) (a) Gurubasavaraj, P. M.; Roesky, H. W.; Nekoueishahraki, B.; Pal, A.; Herbst-Irmer, R. Inorg. Chem. 2008, 47, 5324–5331. (b) Mandal, S. K.; Gurubasavaraj, P. M.; Roesky, H. W.; Oswald, R. B.; Magull, J.; Ringe, A. Inorg. Chem. 2007, 46, 7594–7600. (c) Gurubasavaraj, P. M.; Mandal, S. K.; Roesky, H. W.; Oswald, R. B.; Pal, A.; Noltemeyer, M. Inorg. Chem. 2007, 46, 1056–1061. (d) Nikiforov, G. B.; Roesky, H. W.; Schulz, T.; Stalke, D.; Witt, M. Inorg. Chem. 2008, 47, 6435–6443.

r 2009 American Chemical Society

Published on Web 09/16/2009

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and structural characterization of five bismuth heterobimetallic complexes with main group and transition metals.

Nekoueishahraki et al. Scheme 1. Preparation of Heterobimetallic Bismuth Complexes, Ar = 2,6-iPr2C6H3

Results and Discussion The μ-O-bridged heterobimetallic bismuth complexes 1,8C10H6(NSiMe3)2Bi( μ-O)MMeL (M = Al 2,Ga 3), 1,8-C10H6(NSiMe3)2Bi( μ-O)GeL (4), 1,8-C10H6(NSiMe3)2Bi( μ-O)ZrMeCp*2 (5), and 1,8-C10H6(NSiMe3)2Bi( μ-O)HfClCp*2 (6) were obtained as yellow solids in good yields from the reaction of the dimethylamino bismuth complex of L1BiNMe2 (1) [L1 = 1,8-C10H6(NSiMe3)2] with the corresponding monometallic hydroxide precursors under elimination of HNMe2, as shown in Scheme 1. Treatment of 1 with stoichiometric amounts of LM(Me)(OH) (M = Al, Ga) in n-hexane at room temperature results in the formation of 2 and 3, exhibiting the Bi-O-M (M=Al 2, Ga 3) moiety. The 1H NMR spectra of the reaction mixture of compounds 2-6 show almost quantitative conversion of the reactants to products, as revealed by the absence of any M-OH and NMe2 resonances. The 1H NMR spectrum of 2 displays two resonances (-0.69 and 0.24 ppm) that can be attributed to the Me protons of AlMe and SiMe3 groups, respectively, whereas the particular GaMe and SiMe3 groups in compound 3 resonate at -0.56 and 0.28 ppm. The mass spectral data of compounds 2-6 are in agreement with the assigned structures. Compound 2 is moderately air and moisture sensitive, but thermally quite stable, as indicated by the high melting point and EI mass spectrum, in which the molecular ion (Mþ) was observed with 100% intensity. The next most intense peak at m/z 969.5 was assigned to [M - Me]þ. Similarly the reaction of 1 with LGe(OH) in n-hexane at room temperature affords 1,8-C10H6(NSiMe3)2Bi( μ-O)GeL (4) in moderate yield (63%). The 1H NMR and 29Si NMR spectra of 4 exhibit singlets at δ 0.24 and 0.99 ppm, respectively, corresponding to the SiMe3 groups. Complex 4 is a yellow crystalline solid that is soluble in common organic solvents such as toluene, THF, and n-hexane and is stable at room temperature for several months under an inert atmosphere. In the mass spectrum of 4 the peak with the highest mass corresponds to the molecular ion Mþ, and the next most intense peak is observed at m/z 599, which can be assigned to the fragment [M - CH(DippNCMe)2]þ. The syntheses of 1,8-C10H6(NSiMe3)2Bi( μ-O)ZrMeCp*2 (5) and 1,8-C10H6(NSiMe3)2Bi( μ-O)HfClCp*2 (6) are accomplished by reacting 1 with Cp*2ZrMe(OH) and the in situ reaction with Cp*2HfCl(OH), respectively. Cp*2HfCl(OH) was prepared from Cp*2HfCl2 and water in the presence of an N-heterocyclic carbene [CN(iPr)C2Me2N(iPr)]. The carbene is used for trapping quantitatively the generated HCl from hydrolysis of Cp*2HfCl2. Compounds 5 and 6 are yellow solids, which are thermally quite stable, as evidenced by their high melting points (206 and 210 °C, respectively) and the presence of molecular ions in their EI mass spectra. 5 is soluble in toluene, THF, and n-hexane, while compound 6 is soluble in toluene and THF only. The 1H and 13C NMR data of 5 and 6 are consistent with the determined single-crystal structures. The 1H NMR spectrum of 5 in C6D6 exhibits three singlets (0.28, 1.63, -0.43 ppm) attributed to the proton resonances arising from SiMe3, η5-C5Me5, and Zr-Me groups, whereas the respective SiMe3 and η5-C5Me5 groups in compound 6 resonate at 0.3 and 1.73 ppm. The 13C NMR spectrum of 5 reveals two resonances (25.7, 11.3 ppm), which can be assigned to the carbon resonances (15) Flack, H. D. Acta Crystallogr. 1983, A39, 876–881.

arising from Zr-Me and Zr-Cp*, respectively. In compound 6 the carbon atoms of the methyl groups (Hf-Cp*) resonate at 11.5 ppm. The mass spectrometry data for 5 revealing a signal of low intensity (m/z 900.29) for the molecular ion and the base peak is observed at m/z 494.1, corresponding to [M-Cp*2Zr(Me) -OMe]þ. In the mass spectrum of compound 6 the base peak is observed at m/z 875.3, representing [M - Cp*]þ, and the peak with the highest mass corresponds to the molecular ion Mþ (m/z 1010.5). Molecular Structure Description of 2-6. Yellow crystals of 2, 3, 4, and 5, suitable for single-crystal X-ray diffraction study, were obtained from a saturated solution of n-hexane at -30 °C and for those of 6 from a mixture of n-hexane/ toluene at -30 °C. Compounds 2-6 are stable in the solid state under an inert atmosphere at room temperature. Crystallographic data for the structural analyses of compounds 2-6 are given in Table 1, and important bond parameters are listed in Table 2. Compounds 2 and 3 crystallize in the monoclinic space group P21/c, with two and one molecule in the asymmetric unit, respectively (Figures 1, 2). The aluminum and gallium atoms each adopt a distorted tetrahedral environment, whereas the coordination geometry around the bismuth atom is that of a distorted pyramidal arrangement with a stereochemically active electron lone pair. The Al-O distance (av 1.834 A˚) is similar to that reported for complex [{Bi(Hsal)3}2{Al(acac)3}] (av 1.871 A˚).11 The Al( μ-O)Bi angle (av 160.6°) in 2 is considerably bigger than the corresponding Al( μ-O)Ga bond angle in 3 (123.25(7)°). The Ga-N bond lengths (1.963(16) and 1.973(16) A˚) and N-Ga-N angle (95.87(6)°) are comparable to those observed in [Me2Ga(2-NC5H4)2CH].16 The angle for the bent Ga-O-Bi linkage is 123.25(7)°, which is considerably more acute than that in LGa(Me)( μ-OH)LnCp3 (Ln = Sm, Nd; av 149.5°). The corresponding Ga-O bond length (1.815(13) A˚) is shorter than the Ga-μ-OH bond in LGa(Me)( μ-OH)LnCp3 (av 1.856 A˚).17 (16) Gornitzka, H.; Stalke, D. Organometallics 1994, 13, 4398–4405. (17) Singh, S.; Pal, A.; Roesky, H. W.; Herbst-Irmer, R. Eur. J. Inorg. Chem. 2006, 4029–4032.

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Table 1. Crystal Data and Structure Refinement for Compounds 2-6

empirical formula fw CCDC no. color cryst syst space group Flack x param15 a, A˚ b, A˚ c, A˚ β, deg V, A˚3 Z Fcalcd, Mg m-3 μ, mm-1 F(000) θ range, deg index ranges

2

3 3 C7H8

4 3 0.5n-hexane

5

6

C46H68AlBiN4OSi2 985.18 739830 yellow monoclinic P21/c

C53H76BiGaN4OSi2 1120.06 736409 yellow monoclinic P21/c

C48H72BiGeN4OSi2 1058.85 736410 yellow monoclinic P21/n

C37H57BiN2OSi2Zr 902.23 736411 yellow monoclinic Pn -0.027(3) 12.364(5) 10.377(4) 15.826(6) 108.472(5) 1925.8(12) 2 1.556 4.927 904 1.83 to 25.36 -14 e h e 14 0 e k e 12 -19 e l e 19 17 310 7013 (0.0290) 1.061 R1 = 0.0260 wR2 = 0.0536 R1 = 0.0279 wR2 = 0.0542 0.627/-1.004

C36H54BiClHfN2OSi2 1009.91 736412 yellow monoclinic Pn -0.041(4) 12.3404(14) 10.3340(11) 15.7596(18) 108.1890(10) 1909.3(4) 2 1.757 7.481 984 1.84 to 26.71 -15 e h e 15 -13 e k e 12 -19 e l e 19 39 941 8051 (0.0294) 1.066 R1 = 0.0245 wR2 = 0.0599 R1 = 0.0251 wR2 = 0.0604 1.122/-1.251

42.529(7) 19.2651(17) 10.1601(17) 10.7195(10) 21.967(4) 26.118(2) 90.324(2) 99.5340(10) 9492(3) 5319.2(8) 8 4 1.379 1.399 3.821 3.894 4032 2288 0.93 to 26.02 2.05 to 26.77 -52 e h e 52 -24 e h e 24 12 e k e 12 0 e k e 13 27 e l e 27 0 e l e 33 no. of reflns 192 453 116 349 18 633 (0.0378) 11 321 (0.0345) no. of indept reflns (Rint) Goof 1.124 1.036 R1 = 0.0176 final R indices (I > 2σ(I )) R1 = 0.0338 wR2 = 0.0747 wR2 = 0.0387 R1 = 0.0212 R1 = 0.0355 R indices (all data)a,b wR2 = 0.0755 wR2 = 0.0397 4.297/-2.532 0.418/-0.403 largest diff peak/hole, e A˚-3 P P P P a R1 = ||Fo| - |Fc||/ |Fo|. b wR2 = [ w(Fo2 - Fc2)2/ w(Fo2)2]0.5.

22.5913(18) 21.8804(17) 22.7918(18) 117.5600(10) 9987.7(14) 8 1.408 4.206 4312 1.05 to 39.39 -40 e h e 35 0 e k e 39 0 e l e 40 461 531 59 552 (0.0528) 1.041 R1 = 0.0339 wR2 = 0.0602 R1 = 0.0490 wR2 = 0.0637 1.952/-2.627

Table 2. Selected Bond Lengths [A˚] and Angles [deg]of 2-6

2

3

4

5

6

M=

Ala

Ga

Gea

Zr

Hf

R=

Me

Me

Me

Cl

M-O Bi-O M-R Bi-N1 Bi-N2 M-L2b M-L3b

1.690(3)/1.707(3) 1.995(4)/1.978(3) 1.959(5)/1.948(5) 2.115(4)/2.131(4) 2.157(4)/2.152(4) 1.902(4)/1.914(4) 1.931(4)/1.914(4)

1.8159(13) 2.0282(13) 1.955(2) 2.1425(17) 2.1443(16) 1.9633(16) 1.9731(16)

Bi-O-M O-Bi-N2c O-M-L3d O-M-R

160.7(2)/160.5(2) 95.6/96.8 122.6/120.7 116.2(2)/117.1(2)

123.25(7) 95.2 115.4 120.06(8)

1.8231(11)/1.8277(11) 2.0493(11)/2.0552(11) 2.1389(14)/2.1329(14) 2.1614(14)/2.1480(14) 2.0261(13)/1.9949(13) 2.0556(13)/2.0438(13) 112.58(6)/125.20(6) 97.2/96.4 99.1/99.4

1.982(3) 2.032(3) 2.292(5) 2.139(4) 2.169(4) 2.277 2.282

1.957(3) 2.045(3) 2.4459(12) 2.139(4) 2.158(4) 2.239 2.249

138.23(19) 98.9 140.3 92.07(18)

134.55(18) 98.9 136.3 92.54(10)

a The two numbers in this column refer to two crystallographically independent molecules in the asymmetric unit. b Two nitrogen atoms in 2, 3, and 4 and two Cp* ring centers in 5 and 6. c Angle of the Bi-O bond to the plane determined by the bismuth atom and the two nitrogen atoms of the ligand. d Angle of the M-O bond to the plane determined by the metal atom and two nitrogen atoms in 2, 3, and 4 and two Cp* ring centers in 5 and 6.

Obviously there is more charge accumulated at the O2- in 3 than at the OH- in the latter complex. Compound 4 crystallizes in the monoclinic space group P21/n with two molecules and one disordered n-hexane in the asymmetric unit. As expected, 4 contains the bismuth atom bonded through an oxygen atom to germanium (Figure 4).

The bismuth and germanium atoms both exhibit a highly distorted pyramidal geometry, involving the chelating 1,8C10H6(NSiMe3)2 ligand and β-diketiminato ligand, the ( μ-O) atom, and a stereochemically active lone pair at each atom. The Ge-N bond lengths (av 2.010 and 2.049 A˚) and N-Ge-N angle (av 87.47°) are comparable to those of

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Figure 1. Molecular structure of 2. Anisotropic displacement parameters are depicted at the 50% probability level. H atoms and disordered SiMe3 groups are omitted for clarity.

Figure 2. Molecular structure of 3. Anisotropic displacement parameters are depicted at the 50% probability level. H atoms and one toluene solvent molecule are omitted for clarity.

Figure 3. Molecular structure of 4. Anisotropic displacement parameters are depicted at the 50% probability level. H atoms and half a molecule of n-hexane are omitted for clarity.

Nekoueishahraki et al.

Figure 4. Molecular structure of 5. Anisotropic displacement parameters are depicted at the 50% probability level. H atoms are omitted for clarity.

oxygen-bridged heterobimetallic complexes reported in ref 18. 4 features a bent Ge-O-Bi (av 118.89°) arrangement with a Ge-O distance of av 1.825 A˚ and a Bi-O bond length of av 2.052 A˚. The Ge-O bond length is longer than those in Ge-O-Yb (1.769 A˚) and Ge-O-Y (1.762 A˚) species19 and is comparable with those in Ge-O-Hf (1.799 A˚) and Ge-O-Zr (1.797 A˚) arrangements.18 Compounds 5 and 6 crystallize in the monoclinic space group Pn with one molecule in the asymmetric unit. Both absolute structures could be determined unequivocally. In 5 the bismuth atom is bonded through an oxygen atom to zirconium and in 6 to hafnium, respectively, and both contain a bent Bi-O-M (M = Zr, Hf) core, as revealed by the corresponding bond angles (138.23(19)° and 134.55(18)°) (Table 2). Like the other structures, the bismuth atom shows the anticipated trigonalpyramidal coordination geometry with two nitrogen atoms of the 1,8-C10H6(NSiMe3)2 ligand and one ( μ-O) atom. The zirconium and hafnium metal atoms show a distorted tetragonal geometry each (Figures 4 and 5). The coordination sphere around the transition metals is quite similar: the zirconium metal in 5 accommodates two of the η5-coordinated Cp* ligands, the μ-bridging O atom, and one Me group, whereas at the hafnium atom in 6 the latter is replaced by a chlorine atom. The Zr-O bond length (1.982(3) A˚) falls between those found in LMeAl( μ-O)ZrRCp2 (av 1.92 A˚)20 and Ti4Zr4O6(OBu)4(OMc)16 (OMc = methacrylate, av Zr-O 2.17 A˚).21 In 6 the Hf-O bond length (1.957(3) A˚) is longer than that in LAlMe( μ-O)HfMeCp2 (1.919 A˚).14c The Bi-O bond length in compounds 3-6 (av 2.038 A˚) is comparable to those observed in (BiTi2O(OiPr)9 (2.090 A˚)22 and [(Cp*2MoO3)BiPh3] (2.201 A˚)23 but considerably shorter than that found in [{Bi(Hsal)3}2{Al(acac)3}] (2.765 A˚).11 (18) Pineda, L. W.; Jancik, V; Roesky, H. W.; Herbst-Irmer, R. Inorg. Chem. 2005, 44, 3537–3540. (19) Yang, Y.; Roesky, H. W.; Jones, P. G.; So, C.-W; Zhang, Z.; Herbst-Irmer, R.; Ye, H. Inorg. Chem. 2007, 46, 10860–10863. (20) Bai, G.; Singh, S.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. J. Am. Chem. Soc. 2005, 127, 3449–3455. (21) Moraru, B.; Kickelbick, G.; Schubert, U. Eur. J. Inorg. Chem. 2001, 1295–1301. (22) Parola, S.; Papiernik, R.; Hubert-Pfalzgraf, L. G.; Jagner, S.; Hakansson, M. J. Chem. Soc., Dalton Trans. 1997, 4631–4635. (23) Roggan, S.; Limberg, C.; Ziemer, B. Angew. Chem. 2005, 117, 5393–5397. Angew. Chem., Int. Ed. 2005, 44, 5259-5262.

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Figure 5. Molecular structure of 6. Anisotropic displacement parameters are depicted at the 50% probability level. H atoms are omitted for clarity.

Structural Comparison of 2-6. The Bi-N bond distances span a very narrow range of 2.115(4) in 2 to 2.169(4) A˚ in 5, while the Bi-O distances vary by about 0.08 A˚ from 1.978(3) in 2 to 2.0552(11) A˚ in 4. The shortest Bi-O bond in the aluminum derivative 2 correlates with the widest Bi-O-M angle (160.7(2)° in 2), while the longer distance in 4 tolerates the most acute angle (112.58(6)°). The angle of the Bi-O bond to the BiN2 plane is remarkably invariant and widens only by less than 4° from 95.2° in 3 to 98.9° in 5 and 6, demonstrating that the lone-pair character at the bismuth atom is almost independent from the nature of the second organometallic fragment. The angle of the M-O bond relative to the ML2 plane varies much more (from 99.1° in 4 to 140.3° in 5), reflecting the dependence of the angle on the steric requirements of the organometallic fragment.

Experimental Section General Comments. All experimental manipulations were carried out under an atmosphere of dry nitrogen using standard Schlenk techniques. The samples for spectral measurements were prepared in a glovebox. The solvents were purified according to conventional procedures and were freshly distilled prior to use. Cp*2ZrMe2 and Cp*2HfCl2 were purchased from Fluka. NMR spectra were recorded on either a Bruker Avance 200 or 500 NMR spectrometer and referenced to the deuterated solvent in the case of the 1H and 13C NMR spectra. 29Si NMR spectra were referenced to SiMe4. All NMR measurements were carried out at room temperature. Melting points were measured in sealed glass tubes on a B€ uchi B-540 melting point apparatus and are uncorrected. Mass spectra were obtained on a Finnigan MAT 8230 spectrometer by the EI technique. Elemental analyses were performed at the Analytical Laboratory of the Institute of Inorganic Chemistry at G€ ottingen. LMeM(OH) (M = Al, Ga),24,25 LGe(OH),26 (L = CH(NAr(CMe))2, Ar = 2,6-iPr2C6H3), Cp*2MeZr(OH),27 and [1,8-C10H6(NSiMe3)2(24) Singh, S.; Kumar, S. S.; Chandrasekhar, V.; Ahn, H.-J.; Biadene, M.; Roesky, H. W.; Hosmane, S. N.; Noltemeyer, M.; Schmidt, H.-G. Angew. Chem. 2004, 116, 5048–5051. Angew. Chem., Int. Ed. 2004, 43, 4940-4943. (25) Singh, S.; Jancik, V.; Roesky, H. W.; Herbst-Irmer, R. Inorg. Chem. 2006, 45, 949–951. (26) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Neculai, D.; Neculai, A. M. Angew. Chem. 2004, 116, 1443–1445. Angew. Chem., Int. Ed. 2004, 43, 1419-1421. (27) Gurubasavaraj, P. M.; Roesky, H. W.; Sharma, P. M. V.; Oswald, R. B.; Dolle, D.; Pal, A. Organometallics 2007, 26, 3346–3351.

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BiNMe2] (1)28 were prepared according to literature procedures. Preparation of 1,8-C10H6(NSiMe3)2Bi( μ-O)AlMeL (2). n-Hexane (40 mL) was added to a mixture of LMeAl(OH) (0.33 g, 0.69 mmol) and 1 (0.38 g, 0.69 mmol). The resulting solution was stirred for 12 h at room temperature. After concentration and keeping the solution at -30 °C in a freezer yellow crystals of 2 were isolated. Yield: 0.47 g (69%); mp 174 °C. 1H NMR (300.13 MHz, C6D6): δ 6.95-7.24 (m, 12H), 4.68 (s, 1H), 3.06-3.18 (m, 4H), 1.47 (s, 6H), 1.31 (d, 6H), 1.14 (d, 6H), 1.08 (d, 6H), 0.99 (d, 6H), 0.24 (s, 18H), -0.69 (s, 3H) ppm. 13C NMR (75.47 MHz, C6D6): δ 169, 146.6, 144.4, 139.9, 137.8, 129.6, 127, 126.2, 124.4, 124.3, 120.2, 116.6, 96.1, 28.6, 27.6, 26.2, 25.1, 24.9, 24.7, 23.2, 3.15, -8.4 ppm. 29Si NMR (59.6 MHz, C6D6): δ 0.26 ppm. EI-MS [m/z (%)]: 984.5 (100) [M]þ, 969 (36) [M - Me]þ. Anal. Calcd for C46H68AlBiN4OSi2 (985.2): C, 56.08; H, 6.96; N, 5.69. Found: C, 55.88; H, 7.11; N, 5.78. Preparation of 1,8-C10H6(NSiMe3)2Bi( μ-O)GaMeL (3). n-Hexane (40 mL) was added to a mixture of LMeGa(OH) (0.37 g, 0.71 mmol) and 1 (0.4 g, 0.71 mmol). The resulting solution was stirred for 12 h at room temperature. Yellow crystals of 3 were isolated from the mixture of an n-hexane/toluene solution (3:1 v/v) at -30 °C in a freezer. Yield: 0.39 g (54%); mp 191 °C. 1H NMR (300.13 MHz, C6D6): δ 6.96-7.23 (m, 12H), 4.57 (s, 1H), 3.15-3.23 (m, 4H), 1.57 (s, 6H), 1.28 (d, 6H), 1.14 (d, 6H), 1.09 (d, 6H), 1.02 (d, 6H), 0.28 (s, 18H), -0.56 (s, 3H) ppm. 13C NMR (125.7 MHz, C6D6): δ 167.7, 146.7, 144.7, 140.4, 137.8, 129.7, 127, 126.2, 124.4, 124.3, 120.2, 116.6, 96, 28.8, 27.8, 26.3, 25.2, 24.7, 24.6, 23.3, 3.17, -6.5 ppm. 29Si NMR (99.3 MHz, C6D6): δ 0.52 ppm. Anal. Calcd for C46H68BiGaN4OSi2 (1027.9): C, 53.75; H, 6.67; N, 5.45. Found: C, 53.26; H, 6.71; N, 5.61. Preparation of 1,8-C10H6(NSiMe3)2Bi( μ-O)GeL (4). n-Hexane (30 mL) was added to a mixture of LGe(OH) (0.32 g, 0.63 mmol) and 1 (0.35 g, 0.63 mmol). The resulting solution was stirred for 12 h at room temperature. After concentration and keeping the solution at -30 °C in a freezer yellow crystals of 4 were isolated. Yield: 0.41 g (63%); mp 251 °C. 1H NMR (300.13 MHz, C6D6): δ 6.91-7.19 (m, 12H), 4.56 (s, 1H), 3.37 (sept, 2H), 3.14 (sept, 2H), 1.47 (s, 6H), 1.28 (d, 6H), 1.20 (d, 6H), 1.04 (d, 6H), 1.07 (d, 6H), 0.24 (s, 18H) ppm. 13C NMR (75.47 MHz, C6D6): δ 162.6, 146.7, 145.2, 144, 139, 137.7, 130.1, 126.8, 126.4, 124.4, 120.5, 116.7, 95, 31.9, 28.7, 28.3, 26.8, 25.1, 24.8, 22.9, 22.6, 14.2, 3.0 ppm. 29Si NMR (59.6 MHz, C6D6): δ 0.99 ppm. EI-MS [m/z (%)]: 1016.4 (100) [M]þ, 599 (62) [M - CH(DippNCMe)2]þ. Anal. Calcd for C48H72BiGeN4OSi2 (1058.85, 4 3 0.5 n-hexane): C7H8): C, 54.39; H, 6.79; N, 5.28. Found: C, 53.64; H, 6.79; N, 5.28. Preparation of 1,8-C10H6(NSiMe3)2Bi( μ-O)ZrMeCp*2 (5). n-Hexane (40 mL) was added to Cp*2MeZr(OH) (0.43 g, 1.1 mmol) and 1 (0.6 g, 1.1 mmol). The resulting solution was stirred for 12 h at room temperature, and then the solvent was partly removed and the solution kept at -30 °C in a freezer. Yellow crystals of 5 were isolated after 2 days. Yield 0.72 g (73%); mp 206 °C. 1H NMR (300.13 MHz, C6D6): δ 7.44-7.47 (m, 2H), 7.17-7.31 (m, 4H), 1.63 (s, 30H), 0.28 (s, 18H), -0.43 (s, 3H) ppm. 13C NMR (75.47 MHz, C6D6): δ 147.2, 138.5, 130.4, 126.8, 120.4, 118.7, 117.2, 25.7, 11.3, 3.07 ppm. 29Si NMR (59.6 MHz, C6D6): δ 1.1 ppm. EI-MS [m/z (%)]: 524.2 (78) [M - Cp*2Zr(Me) - H]þ, 494.1 (100) [M - Cp*2Zr(Me) - OMe]þ. Anal. Calcd for C37H57BiN2OSi2Zr (902.23): C, 49.25; H, 6.37; N, 3.10. Found: C, 48.78; H, 6.39; N, 3.19. Preparation of 1,8-C10H6(NSiMe3)2Bi( μ-O)HfClCp*2 (6). To a solution of Cp*2HfCl2 (0.445 g, 0.846 mmol) and [CN(iPr)C2Me2N(iPr)] (:C, 0.15 g, 0.846 mmol) in toluene (60 mL) was slowly added degassed and distilled water (15 μL, 0.846 mmol) under vigorous stirring over a period of 30 min. The mixture was (28) (a) Nekoueishahraki, B.; Sarish, S. P.; Roesky, H. W.; Stern, D.; Schulzke, C.; Stalke, D. Angew. Chem. 2009, 121, 4587–4590. Angew. Chem., Int. Ed. 2009, 48, 4517-4520. (b) Wirringa, U.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. Inorg. Chem. 1994, 33, 4607–4608.

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Nekoueishahraki et al.

stirred for another 30 min, and the formation of a white precipitate was observed. The resulting solid was filtered off, and the filtrate was added to a flask containing 1 (0.47 g, 0846 mmol) at -30 °C. The mixture was stirred for 1 h at this temperature and then was allowed to attain room temperature, and stirring was continued for 12 h. All volatiles were removed in vacuo, and the resulting solid was washed with n-hexane (20 mL) to give yellow crystalline 6. The product was recrystallized from a toluene/ n-hexane (2:1 v/v) mixture to yield yellow crystals. Yield: 0.29 g (34%); mp 210 °C. 1H NMR (300.13 MHz, C6D6): δ 7.44-7.47 (m, 2H), 7.22-7.34 (m, 4H), 1.73 (s, 30H), 0.3 (s, 18H) ppm. 13C NMR (75.47 MHz, C6D6): δ 147.8, 138.5, 126.8, 120.3, 119.6, 116.8, 11.5, 2.9 ppm. 29Si NMR (59.62 MHz, C6D6): δ 1.12 ppm. EI-MS [m/z (%)]: 1010.5 (43) [M]þ, 875 (100) [M - Cp*]þ. Anal. Calcd for C36H54BiClHfN2OSi2 (1009.91): C, 42.77; H, 5.34; N, 2.77. Found: C, 42.40; H, 5.35; N, 2.80. Crystallographic Details for Compounds 2-6. Single crystals were selected from the Schlenk flasks under an argon atmosphere and covered with perfluorinated polyether oil on a microscope slide, which was cooled with a nitrogen gas flow using the X-TEMP2.29 An appropriate crystal was selected using a polarizing microscope, mounted on the tip of a glass fiber, fixed to a goniometer head, and shock cooled by the crystal cooling device.30 For 3 data were collected on a Bruker TXS rotating anode with a D8 goniometer at 100 K (Mo KR radiation, λ=71.073 pm; INCOATEC Helios multilayer mirror optics), and for 2 and 4-6 data were collected on a Bruker SMART-APEX II diffractometer with a D8 goniometer and an INCOATEC IμS microsource plus Quazar multilayer mirror optics at 100 K (Mo KR radiation, λ = 71.073 pm).31 The data were integrated with SAINT,32 and a semiempirical absorption correction from equivalents was applied.33 The structures were solved by direct methods (SHELXS) and refined on F2 using the

full-matrix least-squares methods of SHELXL.34 All non-hydrogen atoms were refined with anisotropic displacement parameters. All hydrogen atoms bonded to sp2 (sp3) carbon atoms were assigned ideal positions and refined using a riding model with Uiso constrained to 1.2 (1.5) times the Ueq value of the parent carbon atom. In compound 2 the unit cell adopts almost orthorhombic geometry caused by a monoclinic angle β. Due to this geometry, a pseudo-merohedral twinning occurs and the structure solution was possible only after taking the twin component into account. The twin matrix (1 0 0 0 -1 0 0 0 -1) describes a 2-fold rotation about the a-axis, and the occupancy of the twin fraction refines to 18%. The structure could be refined satisfactorily except for the residual electron density appearing close to the Bi atoms, which is a little high (max 4.3 with 0.65 A˚ from Bi2 and min -2.5 with 1.58 A˚ from Bi1) but still in the acceptable 5% range of these heavy atoms. Crystal data and selected bond lengths and angles are shown in Tables 1 and 2. Crystallographic data (excluding structure factors) have been deposited with the Cambridge Crystallographic Centre; the CCDC numbers are listed in Table 1. Copies of the data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif.

(29) (a) Kottke, T.; Stalke, D. J. Appl. Crystallogr. 1993, 26, 615–619. (b) Stalke, D. Chem. Soc. Rev. 1998, 27, 171–178. (30) Kottke, T.; Lagow, R. J.; Stalke, D. J. Appl. Crystallogr. 1996, 29, 465–468. (31) Schulz, T.; Meindl, K.; Leusser, D.; Stern, D.; Graf, J.; Michaelsen, C.; Ruf, M.; Sheldrick, G. M.; Stalke, D. J. Appl. Crystallogr. 2009, in press. (32) SAINT v7.34A in Bruker APEX v2.1-0; Bruker AXS Inst. Inc.: Madison, WI, 2008. (33) Sheldrick, G. M. SADABS 2008/1/TWINABS 2008/1; G€ottingen, Germany, 2008.

Acknowledgment. Support of the Deutsche Forschungsgemeinschaft is highly acknowledged. We thank Bruker axs and CHEMETALL for their support.

Conclusion We described the synthesis and characterization of heterobimetallic bismuth complexes bearing the Bi-O-M motif. These complexes have been obtained by using the Br€ onsted acidic hydroxide precursors. This facile and efficient synthetic method opens up unique opportunities for the generation of heterobimetallic bismuth complexes applicable to a wide range of main group elements and transition metals.

Supporting Information Available: X-ray data for 2, 3, 4, 5, and 6 (CIF). This material is available free of charge via the Internet at http://pubs.acs.org. (34) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112–120.