Thermodynamically controlled Reactions of Selenenylphosphonium Ion Me3PSeMe+ toward Electrophiles and Nucleophiles

Lewis base adducts with selenenyl halides have been investigated experimentally and theoretically as models for interactions that might be relevant for the activity of Glutathione peroxidase (GPx).[1-3] Recently, we have shown that in donor adducts of selenenium ions with amines or phosphanes the formal donor-acceptor bond is covalent rather than dative.[4] Our findings suggested that in contrast to the description of adducts of the isolobal arsenium ions a description as selenenyl phosphonium and selenenyl ammonium ions appears more appropriate (Scheme 1). We also prepared compounds containing the selenenylphosphonium ion on a synthetic scale and studied their spectroscopic and chemical behaviour.[5] Here we describe ab-initio calculations exploring the reactivity of methyl substituted selenenyl phosphonium ions towards some simple nucleophiles and electrophiles.