Radical cations of phenyl silatrane.

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, aαHax = 37.93 G, aαHlat = 0.23 G and aβH = 1.8 G). EPR spectroscopy and DFT calculations attest that the unpaired electron in the radical cation does not reside at the Si atom.