Insertion of Silylenes into Si鈥揌 and Si鈥揅l Bonds. Comparison of Mechanism and Substituent Effects

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• 作者：Zheng Xu ; Juan Jin ; Haixia Zhang ; Zhifang Li ; Jianxiong Jiang ; Guoqiao Lai ; Mitsuo Kira
• 刊名：Organometallics
• 出版年：2011
• 出版时间：June 27, 2011
• 年：2011
• 卷：30
• 期：12
• 页码：3311-3317
• 全文大小：854K
• 年卷期：v.30,no.12(June 27, 2011)
• ISSN：1520-6041

文摘

Electronic and steric substituent effects on the insertion reactions of dimethylsilylene (1) and 2,2,5,5-tetrasilylsilacyclopentane-1,1-diyl (2鈥?/b>) into Si鈥揌 bonds are compared with those into Si鈥揅l bonds using DFT calculations at the B3LYP/6-31++G(d,p) level. For both 1 and 2鈥?/b>, the 螖G value for the insertion into a Si鈥揌 bond of SiH₄ is close to and only ca. 1.5 kcal mol^鈥? lower than that into the Si鈥揅l bond of H₃SiCl. Effects of in-plane substituents on the 螖G values for both Si鈥揌 and Si鈥揅l insertion reactions are mainly electronic and electron-withdrawing substituents lower the 螖G values. Sensitivity of the Si鈥揌 insertion to the substituent effects is similar to that of the Si鈥揅l insertion. Effects of out-of-plane substituents are largely steric, and their sensitivity for the Si鈥揌 insertion is close to that for the Si鈥揅l insertion. The 螖G values for the insertion reactions of sterically bulky 2鈥?/b> are significantly larger than those of 1. The puzzling prior observation that a bulky isolable silylene inserts into the Si鈥揅l bond of H₂SiCl₂ and the Si鈥揌 bond of Me₂SiHCl is explained on the basis of the substituent effects on the insertion reactions.