Unstable intermediates. Part XCVII. Electron spin resonance spectra and structures of radicals in γ-irradiated aluminium alkyls, trialkyl phosphines, and alkylphosphonium salts

Abstract

Radicals of type R2Ċ–X (R = H or alkyl, X = alkyl-substituted Al or P) have been identified in the title systems. Trends in the magnetic parameters are compared with those for other radicals in this general class, and it is concluded that in all cases, spin is transmitted to the group X by spin-polarisation of the C–X σ-bonding electrons and that the sign of Aiso(X) is negative. The weight of evidence is strongly against any significant C–X dπ–pπ bonding in the ground state of these radicals.