Ionic SNi‐Si Nucleophilic Substitution in N‐Methylaniline‐Induced Si−Si Bond Cleavages of Si2Cl6

AbstractN‐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 SNi‐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 SNi‐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−nSiHCln (n=0–2) and (NMePh)4−nSiCln (n=2–3), are the Si−Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic SNi‐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.