A quantum chemical B3LYP/cc-pVDZ study on bisubstituted silenes indicates that substitution at the carbon atom is more effective than that at the silicon atom at inducing a bent structure. π-Electron-donating substituents at the carbon atom drive the polarized π electrons toward the silicon atom. This reversed polarization effect induces bending of the silylene fragment. The local bending can be interpreted in terms of the second-order Jahn-Teller effect with the "transition density" of πσ* localized substantially at the Si atom. From the series of silenes having increasing bending of the SiH2 unit, we have found that the structure of the SiH2 fragment gradually shifts to a singlet silylene-like geometry. Thus, the covalently bonded SiH2 fragments can evolve into datively bonded fragments of the singlet valence state in the bent silenes, which is a finding that is in accord with the CGMT model.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry