Substituent effects in radical cations of linear oligosilanes

The dependence was analyzed of the first ionization potential I(Si-Si) corr esponding to detachment of an electron from the sigma(Si-Si) highest occupi ed molecular orbital on the parameters of organic (X = Me, Et, Bu-t, Ph, CH =CH2), inorganic (X = F, Cl, Br), and organosilicon (X = SiR3; R is organic radical) substituents in di-, tri-, and tetrasilanes X3SiSiX3. It was foun d by correlation analysis that out of the three possible effects of substit uents X (the inductive, polarizability, and resonance effects), only the fi rst two of them affect the I(Si-Si) values. This means that no conjugation between the substituent X and the radical cation center occurs in X3Si.+/-S iX3.