Phosphine Coordination Complexes of the Diphenylphosphenium Cation: A Versatile Synthetic Methodology for P−P Bond Formation

A series of phosphine−diphenylphosphenium donor−acceptor cationic complexes have been
synthesized and comprehensively characterized (phosphine = diphenylchlorophosphine, triphenylphosphine,
trimethylphosphine, and tricyclohexylphosphine). The complexes involve homoatomic P−P coordinate bonds
that are susceptible to ligand exchange reactions highlighting a versatile new synthetic method for P−P
bond formation. Phosphenium complexes of 1,2-bis(diphenylphosphino)benzene and 1,2-bis(tert-butylphosphino)benzene undergo unusual rearrangements to give a “segregated” diphosphine−phosphonium cation
and a cyclic di(phosphino)phosphonium cation, respectively. The rearrangement products reveal the kinetic
stability of the phosphine−phosphenium bonding arrangement.