PHOTOELECTRON-SPECTRA AND MOLECULAR-PROPERTIES .122. THE LOW 1ST IONIZATION ENERGIES OF THE BETA-TRIMETHYLSILYL SUBSTITUTED SULFIDES (H3C)3SIH2CSCH2SI(CH3)3 AND ((H3C)3SI)3CSCH3 AND THEIR RATIONALIZATION

The rather low first vertical ionization energies of bis(trimethylsilylmethyl)sulfide, IEv1 = 8.04 eV, and tris(trimethylsilyl)methylmethyl sulfide, IEv1 = 7.66 eV, are compared with those of other alkyl, silylalkyl and silylsulfides and shown further to confirm the small influence of α-trimethylsilyl groups and of the very large donor effect of β-trimethylsilyl substituents in the ground state of radical cations. The overall 2.8 eV (!) lowering of the sulfur τ lone pair ionization and of the individual, mostly non-additive, substituent effects, are rationalized in terms of a qualitative approach based on the electron distribution in the ground state of the neutral molecules. © 1990.