Donor-Stabilized Silyl Cations. 3. Ionic Dissociation of Hexacoordinate Silicon Complexes to Pentacoordinate Siliconium Salts Driven by Ion Solvation<sup>1</sup>
Neutral hexacoordinate silicon complexes 1 undergo an equilibriumdissociation to ionic siliconium chlorides 6 at low temperatures in polar solvents: chloroform, dichloromethane, and fluorodichloromethane. The extent of dissociation increases with decreasing temperature, despite the formation of two ions from each molecule. The reaction enthalpies and entropies for the ionizations are negative, and