Semi-empirical MNDO-SCF study of the molecular and electronic structures of some permethylated σ* radicals
Abstract
Molecular and electronic structures have been calculated, using the MNDO method, for a range of permethylated σ* radicals, of general constitution MenM[graphic omitted]M′Men′. When M = M′, radicals based upon second-row M are all calculated to be genuine σ* radicals, but when M is a first-row element, all the systems studied except for Me6C2– are calculated to be very weak complexes of MenM: and Men˙ having long M ⋯ M distances; Me6C2– is calculated to dissociate completely to Me3C– and Me3C˙. When M ≠ M′ and M is a first-row element and M′ is a second-row element, genuine σ* radicals are formed only when M and M′ are together of low electronegativity: high electronegativity of M and M′ leads either to weak complexes of MenM: + Men′M′˙ or to complete dissociation.