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

Nickel complexes of a PC_carbeneP pincer ligand framework are described. Dehydrobromination of the precursor (PC_sp³P)­NiBr in the presence of a donor (PPh₃ or NC^tBu) 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.