Carbon dioxide binding at a Ni/Fe center: synthesis and characterization of Ni(η-CO-κ) and Ni-μ-CO-κ:κ,'-Fe.

The degree of CO activation can be tuned by incorporating a distinct electronic coordination environment at the nickel center. A mononuclear nickel carboxylate species (Ni-CO, ) and a dinuclear nickel-iron carboxylate species (Ni-CO-Fe, ) were prepared. The structure of reveals a rare η-κ binding mode of CO, while that of shows bridging CO binding (μ-κ:κ,') between the nickel and iron, presented as the first example of a nickel-μ-CO-iron species. The structural analyses of and based on XRD and DFT data reveal a higher degree of CO activation in , imparted by the additional interaction with an iron ion.