Chemistry of C-Trimethylsilyl-Substituted Heterocarboranes. 32. Synthetic and Structural Investigations on Half-Sandwich Lanthanacarboranes: Important Synthons in Metallacarborane Chemistry

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• 作者：Jianhui Wang ; Joanna Smith ; Chong Zheng ; John A. Maguire ; Narayan S. Hosmane
• 刊名：Organometallics
• 出版年：2006
• 出版时间：August 14, 2006
• 年：2006
• 卷：25
• 期：17
• 页码：4118 - 4130
• 全文大小：239K
• 年卷期：v.25,no.17(August 14, 2006)
• ISSN：1520-6041

文摘

The reactivities of the monosodium-complexed carborane precursors nido-1-Na(C₄H₈O)-2-(R)-3-(SiMe₃)-2,3-C₂B₄H₅ (R = SiMe₃ (1) or Me (2)) with a number of lanthanide halides were investigated. Thereaction of LnCl₃ (or LnBr₃) with 1 in a 1:2 molar ratio in dry THF at 60 C produced the dimerizedhalf-sandwich lanthanacarborane complexes [2,3-(SiMe₃)₂-1-X-1-(THF)_m-1-Ln(⁵-2,3-C₂B₄H₄)]₂·n(THF)(3, Ln = Y, X = Cl, m = 2, n = 1; 4, Ln = La, X = Br; m = 1, n = 0; 5, Ln = Ce, X = Br; m = 1,n = 0; 6, Ln = Pr, X = Br; m = 2, n = 1; 7, Ln = Nd; X = Cl, m = 2, n = 1; 8, Ln = Sm; X = Br,m = 2, n = 0; 9, Ln = Gd; X = Cl, m = 2, n = 1; 10, Ln = Tb, X = Cl, m = 2, n = 1; 11, Ln = Dy,X = Cl, m = 2, n = 1; 12, Ln = Ho, X = Cl, m = 2, n = 1; 13, Ln = Er, X = Cl, m = 2, n = 1; 14,Ln = Tm, X = Cl, m = 2, n = 1; 15, Ln = Yb, X = Cl, m = 2, n = 1; 16, Ln = Lu X = Cl, m = 2,n = 1) as crystalline solids in 70-92% isolated yields. In a similar manner, the reactions of 2 with LnCl₃at 65 C gave the corresponding complexes [2-Me-3-(SiMe₃)-1-Cl-1-(THF)₂-1-Ln(⁵-2,3-C₂B₄H₄)]₂ (17,Ln = Nd; 18, Ln = Dy; 19, Ln = Ho; 20, Ln = Er; 21, Ln = Yb) as crystalline solids in 72-80% yield.In both series of the reactions, 1 equiv of the particular neutral carborane was also produced. Thesubstitution of the chloride ions in complexes 17 and 20 by 2 gave the half-sandwich lanthanacarboraneclusters {2-Me-3-(SiMe₃)-1-[4,5-(-H)-nido-2-Me-3-(SiMe₃)-2,3-C₂B₄H₅]-1-Ln(⁵-2,3-C₂B₄H₄)}₂·n(THF)(22, Ln = Nd, n = 2; 24, Ln = Er, n = 1) as crystalline solids in 82-87% yield. The reaction of 19 and2 produced the trimer {2-Me-3-(SiMe₃)-1-[4,5-(-H)-nido-2-Me-3-(SiMe₃)-2,3-C₂B₄H₅]-1-Ho(⁵-2,3-C₂B₄H₄)}₃·8(THF) (23) in 57% yield. Complexes 22, 23, and 24 could directly be obtained in good yield(56-67%) from the reaction of 2 with the corresponding LnCl₃ at 65 C in molar ratios of 3:1 in dryTHF. Similarly, the mixed coordinated complex {2,3-(SiMe₃)₂-1-[4,5-(-H)-(nido-2-Me-3-(SiMe₃)-2,3-C₂B₄H₅)]-1-Gd(⁵-2,3-C₂B₄H₄)}₂·3(THF) (25) was obtained by reacting compound 9 with 2. To investigatethe importance of the halide in these reactions, (⁵-Cp)LnCl₂ (Ln = Tb, Dy, Er) with 1 in a 1:2 molarratio produced lanthanacarborane complexes [1-(⁵-C₅H₅)-2,3-(SiMe₃)₂-1-Ln(⁵-2,3-C₂B₄H₄)]₂·n(THF)(26, Ln = Tb, n = 2; 27, Ln = Dy, n = 2; 28, Ln = Er, n = 3) as crystalline solids in 77-82% isolatedyields. On the other hand, the reactions of (⁵-Cp)₂ErCl and (⁸-C₈H₈)GdCl with 1 in 1:1 molar ratiosdid not produce the half-sandwich lanthanacarboranes, but rather gave the exo-polyhedral products {exo-(⁵-C₅H₅)₂Er[4,5-(-H)-2,3-(SiMe₃)₂-2,3-C₂B₄H₄]}·(THF) (29) and {exo-(⁸-C₈H₈)Gd[4,5-(-H)-2,3-(SiMe₃)₂-2,3-C₂B₄H₄]·2(THF) (30) as crystalline solids in 76% and 73% isolated yield, respectively. Allcompounds were characterized by IR spectroscopy and elemental analysis, whereas compounds 3, 7-9,10-16, 18-22, 29, and 30 were characterized by single-crystal X-ray diffraction studies. The diamagneticcompounds 3, 4, and 16 were additionally characterized by ¹H, ¹³C, and ¹¹B NMR spectroscopy.