Unusual Reactivity of cyclo-(P 5 Ph 5 ) : Oxidative Addition at a Group 6 Metal Carbonyl and Insertion of Acetonitrile into a P–P Bond

The reaction of [M(CO) 4 L x ] {M = Cr, W, L = MeCN, x = 2; M = Mo, L = 2,5-norbornadiene (nbd), x = 1} with cyclo-(P 5 Ph 5 ) led to an unusual transformation reaction including the oxidative addition of a P–P bond to the Group 6 metal carbonyl, the insertion of MeCN into a P–P bond, and the formation of an M–M bond. The products were characterized by IR and 31 P{ 1 H} NMR spectroscopy, ESI mass spectrometry and single crystal X-ray crystallography. The complexes contain a metal–metal unit bridged by two terminal phosphanido groups of the novel ligand, (PPh-PPh-PPh-PPh-CMe=N-PPh) 2– . The 31 P{ 1 H} NMR spectrum shows an ABCDE spin system consistent with the molecular structure observed in the solid state. Furthermore, the thermal properties of the complexes were evaluated.