CPh3 as a functional group in P-heterocyclic chemistry: elimination of HCPh3 in the reaction of P-CPh3 substituted Li/Cl phosphinidenoid complexes with Ph2C=O.

P-CPh3 substituted oxaphosphirane complexes 3 were prepared using Li/Cl phosphinidenoid complexes 2 (M = Cr, Mo, W) and benzaldehyde. Employing 2 and benzophenone resulted in the formation of oxaphospholane complexes 4 and 5, the former bearing a benzo[c]-1,2-oxaphospholane and the latter a novel pentacyclic P-ligand. According to DFT studies the latter P-heterocycle arises from formal dimerization of a transient benzofused 2-phosphafurane complex 8, one of the fragments undergoing water-catalyzed [1,3]H shift (4) and the other (11) formed via elimination of HCPh3.