Carbon dioxide binding at a Ni/Fe center: synthesis and characterization of Ni(η(1)-CO(2)-κC) and Ni-μ-CO(2)-κC:κ(2) O,O′-Fe

The degree of CO(2) activation can be tuned by incorporating a distinct electronic coordination environment at the nickel center. A mononuclear nickel carboxylate species (Ni–CO(2), 3) and a dinuclear nickel–iron carboxylate species (Ni–CO(2)–Fe, 5) were prepared. The structure of 3 reveals a rare η(1)-κC binding mode of CO(2), while that of 5 shows bridging CO(2) binding (μ(2)-κC:κ(2) O,O′) between the nickel and iron, presented as the first example of a nickel-μ-CO(2)-iron species. The structural analyses of 3 and 5 based on XRD and DFT data reveal a higher degree of CO(2) activation in 5, imparted by the additional interaction with an iron ion.