Reaction of Terminal Phosphinidene Complexes with Dihydrogen

The reaction of H2 with [RP-W­(CO)5] (R =
Ph, Me) above 120 °C leads, first, to the secondary diphosphine
complex (RPH-PHR)­(W­(CO)5)2 and then to the primary
phosphine complex (RPH2)­(W­(CO)5). On the basis
of DFT calculations, the mechanism most likely involves the addition
of H2 to the P–W bond, followed by the formation
of the radical [RPH-W­(CO)5]• by homolysis
of the W–H bond. In the case of [PhNHP-W­(CO)5],
the hydrogenolysis takes place at the P–N bond and ultimately
produces the secondary diaminophosphine complex ((PhNH)2PH)­(W­(CO)5).