Zhang Jie, Xie Ju, Lee Myong Euy, Zhang Lin, Zuo Yujing, Feng Shengyu
Key Laboratory of Special Functional Aggregated Materials and, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P.R. China.
College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, P.R. China.
Chemistry. 2016 Mar 24;22(14):5010-6. doi: 10.1002/chem.201504927. Epub 2016 Feb 24.
N-Methylaniline-induced Si-Si bond cleavage of Si2Cl6 has been theoretically studied. All calculations were performed by using DFT at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) levels. An ionic SN i-Si nucleophilic substitution mechanism, which is a newly found nucleophilic substitution in silicon-containing compounds, is proposed in the N-methylaniline-induced Si-Si bond cleavage in Si2Cl6. Unlike general S(N)i-Si nucleophilic substitutions that go through a pentacoordinated silicon transition state, ionic nucleophilic substitution goes through a tetracoordinated silicon transition state, in which the Si-Si bond is broken and siliconium ions are formed. Special cleavage of the Si-Si bond is presumably due to the good bonding strength between Si and N atoms, which leads to polarization of the Si-Si bond and eventually to heterolytic cleavage. Calculation results show that, in excess N-methylaniline, the final products of the reaction, including (NMePh)(3-n) SiHCl(n) (n=0-2) and (NMePh)(4-n) SiCl(n) (n=2-3), are the Si-Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic S(N)i-Si nucleophilic substitution mechanism can also be employed to describe the amination of chlorosilane by N-methylaniline. The suggested mechanisms are consistent with experimental data.
对N-甲基苯胺诱导的Si₂Cl₆中Si-Si键断裂进行了理论研究。所有计算均采用密度泛函理论（DFT），在MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p)水平上进行。在N-甲基苯胺诱导的Si₂Cl₆中Si-Si键断裂过程中，提出了一种离子型SN i-Si亲核取代机理，这是在含硅化合物中新发现的亲核取代。与一般通过五配位硅过渡态进行的S(N)i-Si亲核取代不同，离子型亲核取代通过四配位硅过渡态进行，在此过程中Si-Si键断裂并形成硅正离子。Si-Si键的特殊断裂可能是由于Si和N原子之间良好的键合强度，这导致Si-Si键极化并最终发生异裂。计算结果表明，在过量的N-甲基苯胺存在下，反应的最终产物，包括(NMePh)(3-n)SiHCl(n)（n = 0 - 2）和(NMePh)(4-n)SiCl(n)（n = 2 - 3），是Si₂Cl₆的Si-Si断裂产物以及前者相应的胺化产物。离子型S(N)i-Si亲核取代机理也可用于描述N-甲基苯胺对氯硅烷的胺化反应。所提出的机理与实验数据一致。
