Interactions of chloromethyldisilanes with tetrakis(dimethylamino)ethylene (TDAE), formation of [TDAE]radical dot+ [Si3Me2Cl7]−

The chlorodisilanes SiClMe2SiClMe2 (1), SiCl2MeSiCl2Me (2), SiCl3SiCl3 (3) and a 9:1 mixture of 2 and SiCl3SiCl2Me (4) were reacted with the electron-rich alkene tetrakis-(dimethylamino)-ethylene (TDAE) in n-hexane as well as in polar solvents. While 1 gave no reaction at all, 3 underwent a disproportionation reaction into SiCl4 and Si(SiCl3)4. Also 2 and mixtures of 2 and 4 were disproportionated into MeSiCl3 (2a) and methylchlorooligosilanes. Additionally a crystalline mixture of Si3Me3Cl6·TDAE (5a) plus Si3Me2Cl7·TDAE (5b) was obtained by reaction of a 9:1 mixture of 2 and 4 with TDAE in n-hexane as well as in 1,2-dimethoxyethane. The reaction of 2 with TDAE in acetonitrile (MeCN) led to a crystalline precipitation of [TDAE]Cl2·MeCN (6·MeCN) in addition to MeSiCl3 and methylchlorooligosilanes. The structures of 5b and 6·MeCN were determined by X-ray crystallography beside their NMR and IR spectroscopic characterization. Compound 5b crystallizes in the monoclinic space group P2/c (Z=4), 6·MeCN in the orthorhombic space group Pna21 (Z=4). The structure of 5b reveals a [TDAE]radical dot+ radical cation and a 1,2-Me2Si3Cl7− anion with a pentacoordinated central silicon atom.