Radical cations of phenyl silatrane

Abstract

Electrochemical oxidation of phenylsilatrane (1) in CH₃CN/0.1 M Bu₄NPF₆ has been studied by voltammetry, UV-Vis and EPR-coupled spectroelectrochemistry supported by DFT calculations. One-electron withdrawal from the HOMO of 1, formed with a predominant contribution of the atrane N atom to the 3c–4e system, results in a short lived radical cation, in which the atrane nitrogen atom is almost planar and carries most of the spin density showing strong coupling with the protons of the axially directed C–H bonds of the three adjacent α-methylene groups (g = 2.0037, a^αH_ax = 37.93 G, a^αH_lat = 0.23 G and a^βH = 1.8 G). EPR spectroscopy and DFT calculations attest that the unpaired electron in the radical cation does not reside at the Si atom.