Bonding studies in group IV substituted anilines

The relative stabilities of the cation radicals of several Group IV substituted anilines have been determined by cyclic voltammetry. They are p -tert-butyl- > m -trimethylsilyl- > p -trimethylsilyl- > p -trimethylgermyl- ⪢ N,N -dimethylaniline radical cation. The order of stability parallels that of the compounds towards protodemetalation. CNDO/2 calculations of the charge distribution in the ground states and cation radicals of the molecules resolve the apparent, anomaly in the rates of protodesilylation of m - and p -trimethylsilyl- N,N -dimethylaniline. A mechanism for the chemical reactions of the radical cations which is consistent with the experimental and theoretical results is proposed. It involves nucleophilic displacement of the metal from the cation radical prior to the coupling of the radicals. The relative stabilities of the radical cations of the silicon compounds are in the same order as the amount of π character of the SiC bond in the radical cation. The CNDO/2 calculations indicate that this π character is due to both ( p-p )π and ( p-d )π interactions in the neutral molecules and in the radical cations.