Two-Coordinate Fe0 and Co0 Complexes Supported by Cyclic (alkyl)(amino) carbenes

The CAAC [CAAC=cyclic (alkyl)(amino) carbene] family of carbene ligands have shown promise in stabilizing unusually low-coordination number transition-metal complexes in low formal oxidation states. Here we extend this narrative by demonstrating their utility in affording access to the first examples of two-coordinate formal Fe-0 and Co-0 [(CAAC)(2)M] complexes, prepared by reduction of their corresponding two-coordinate cationic Fe-I and Co-I precursors. The stability of these species arises from the strong sigma-donating and p-accepting properties of the supporting CAAC ligands, in addition to steric protection.