Single Electron Pnicogen Bonded Complexes

Abstract

A theoretical study of the complexes formed by monosubstituted phosphines (XH₂P) and the methyl radical (CH₃) has been carried out by means of MP2 and CCSD­(T) computational methods. Two minima configurations have been obtained for each XH₂P:CH₃ complex. The first one shows small P–C distances and, in general, large interaction energies. It is the most stable one except in the case of the H₃P:CH₃ complex. The second minimum where the P–C distance is large and resembles a typical weak pnicogen bond interaction shows interaction energies between −9.8 and −3.7 kJ mol^–1. A charge transfer from the unpaired electron of the methyl radical to the P–X σ* orbital is responsible for the interaction in the second minima complexes. The transition state (TS) structures that connect the two minima for each XH₂P:CH₃ complex have been localized and characterized