C1 molecule activation by POCsp2OP-ligated nickel complexes.

This contribution describes the reactivity of POCsp2OP-supported nickel siloxide (1) and arylamide (2) complexes (POCsp2OP = κP,κC,κP'-2,6-(i-Pr2PO)2C6H3, Ar = 2,6-iPr2-C6H3) toward CO, CO2, H2O, and isonitriles. The amide complex 2 activates CO to form the carbamoyl species 3, whereas the siloxide analogue 1 remains inert under identical conditions. Notably, 3 is also accessible via isonitrile insertion into 1, while the treatment of 2 with ArNC triggers pincer framework disassembly, yielding the doubly hydrogen-bonded phenolate complex 4. The two complexes exhibit contrasting CO2 activation modes: 2 undergoes irreversible Ni-N insertion to form the carbamate 6, whereas 1 engages in reversible CO2 binding to generate the dinuclear carbonate complex 7. These results demonstrate that the ligand rigidity and X-ligand identity synergistically control activation pathways, further highlighting the role of the supporting ligand in harmonizing stability and reactivity during small-molecule incorporation.