Addition of H2 Across a Cobalt-Phosphorus Bond.

Addition of H2 across the cobalt-phosphorus bond of (PPP)CoPMe3 (3) is demonstrated, where PPP is a monoanionic diphosphine pincer ligand with a central N-heterocyclic phosphido (NHP- ) donor. The chlorophosphine CoII complex (PPCl P)CoCl2 (2) can be generated through coordination of the chlorophosphine ligand (PPCl P, 1) to CoCl2 . Subsequent reduction of 2 with KC8 in the presence of PMe3 generates (PPP)CoPMe3 (3), in which both the phosphorus and cobalt centers have been reduced. The addition of 1 atm of H2 to complex 3 cleanly affords (PPH P)Co(H)PMe3 (4), in which H2 has ultimately been added across the metal-phosphorus bond. Complex 4 was characterized spectroscopically and using computational methods to predict its geometry.