Palladium(II) complexes of bis(diphosphene) with different coordination behaviors.

Organophosphorus compounds possessing a P-P double-bond character are intriguing materials in coordination chemistry because it is possible to form a variety of coordination modes from the π-bond in addition to the lone pairs. We report herein the complexation of a new bidentate ligand, ethylene-tethered bis(binaphthyldiphosphene) (,)-2, with palladium(II) species. The reaction of (,)-2 with [Pd(π-allyl)(cod)](SbF) and PdCl(cod) afforded η/η-bis(diphosphene) complex 7 and η-diphosphene/η-phosphanylphosphide complex 8, respectively. The latter was characterized by a chloride migration from the palladium atom to a phosphorus atom due to the high electron-accepting character of the PP moiety. Theoretical calculations revealed the migration process and nature of complex 8.