Cooperative activation of O-H and S-H bonds across the Co-P bond of an N-heterocyclic phosphido complex.

Metal-ligand cooperation has proven to be a viable concept for σ bond activation and catalysis, however there are few examples involving phosphorus as an active participant in bond cleavage. The reactivity of E-H bonds (E = S, O) across a metal-phosphorus bond of a cobalt(i) center ligated by a tridenate N-heterocyclic phosphido (NHP-) ligand with diphosphine sidearms, (PPP)-, has been explored. Addition of PhOH to (PPP)CoPMe3 (1) cleanly affords (PPOPhP)Co(H)PMe3 (2), in which the O-H bond was heterolytically cleaved across the M-PNHP bond. Addition of PhSH to 1 first generates (PPHP)Co(SPh)PMe3 (3), which undergoes an intermolecular rearrangement to generate (PPSPhP)Co(H)PMe3 (4) as the thermodynamic product. A comparison with a related platinum(ii) system reveals the subtle effects that variations in metal intrinsic properties can have on metal-ligand bifunctional σ bond activation processes.