Acyclic catena-Diphosphinodiphosphonium Dications [R3P-PR‘-PR‘-PR3]2+ or Bisphosphine−Diphosphenium Complexes [R3P→PR‘-PR‘←PR3]2+:  Synthesis by Reductive P−P Coupling of [R3P-PR‘Cl]+ and Phosphine Ligand Exchange

The acyclic tetraphosphorus dication [Ph3P-PPh-PPh-PPh3]2+ has been formed by the reductive coupling of [Ph3P-PPhCl]+, providing a new synthetic method for the systematic development of catena-phosphorus cations. Ligand exchange (Ph3P for Me3P) gives [Me3P-PPh-PPh-PMe3]2+, implicating these dications as bisphosphine−diphosphenium complexes.