Unusual tripodal ligands. Synthesis of 2,2-bis( diphenylphosphinomethyl) -l-phenylthiopropane and its group VI complexes

A hybrid tripodal ligand containing phosphorus and sulfur atoms, 2,2-bis(diphenylphosphinomethyl)-1-phenylthiopropane (P,S), was synthesized and its metal carbonyl complexes (P,S)M(CO), (M = Cr, MO and W) were prepared. All synthetic intermediates and complexes have been characterized by spectroscopic methods and elemental analysis. The spectroscopic identification of complexes shows that the P,S ligand behaves as a bidentate ligand with two phosphorus atoms coordinating to the metal center. The structure was confirmed by a crystal structure study of (P,S)Mo(CO),, which revealed an octahedral coordination around the molybdenum atom, and two cis-coordinated phosphorus donors. The conformation of the six-membered chelate ring is a twisted-boat and the possible reasons for this conformational arrangement are discussed.