Activation of Water, Ammonia, and Other Small Molecules by PCcarbeneP Nickel Pincer Complexes

Nickel complexes of a PCcarbeneP pincer ligand framework are described. Dehydrobromination of the precursor (PCsp3P)NiBr in the presence of a donor (PPh3 or (NCBu)-Bu-t) leads to the title complexes, which feature a rare nickel-carbene linkage as the pincer ligand anchor point. This strongly donating, nucleophilic carbene center engages in a variety of E-H bond activations (E = H, C, N, O), some of which are reversible. This represents a new mode of bond activation by ligand cooperativity in nickel pincer complexes.