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

Abstract

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 (PP^OPhP)Co(H)PMe₃ (2), in which the O–H bond was heterolytically cleaved across the M–P^NHP bond. Addition of PhSH to 1 first generates (PP^HP)Co(SPh)PMe₃ (3), which undergoes an intermolecular rearrangement to generate (PP^SPhP)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.