Synthesis and Structural Characterization of Bimetallic Iron−Nickel Carbido Cluster Complexes

In acetonitrile solvent, Fe5(CO)15(μ5-C), 1, reacts with Ni(COD)2 at room temperature to afford the iron−nickel complex Fe5Ni(NCMe)(CO)15(μ6-C), 3. The acetonitrile ligand in 3 can be replaced by CO and NH3 to yield Fe5Ni(CO)16(μ6-C), 4, and Fe5Ni(NH3)(CO)15(μ6-C), 6, respectively. When refluxed in acetonitrile solvent, compound 3 loses a vertex to form the square pyramidal Fe4Ni complex Fe4Ni(NCMe)2(CO)12(μ5-C), 7. Compound 7 readily converts to Fe4Ni(NCMe)(CO)13(μ5-C), 8, by losing one of its acetonitrile ligands. Addition of acetonitrile to 8 gives compound 7. When heated to 110 °C under an atmosphere of CO, both compounds 7 and 8 furnish the octahedral Fe4Ni2 complex Fe4Ni2(CO)15(μ6-C), 9. All six compounds were structurally characterized by single-crystal X-ray diffraction analyses.