The redox chemistry of [Ni9C(CO)17]2âand [Ni10(C2)(CO)16]2â: Synthesis, electrochemistry and structure of [Ni12C(CO)18]4âand [Ni22(C2)4(CO)28(Et2S)]2â

This paper reports a detailed study of the oxidation and reduction reactions of simple nickel mono-carbide and mono-acetlyde carbonyl clusters. The reduction of [Ni9C(CO)17]2âwith Na/naphtalene affords the new [Ni12C(CO)18]4âmono-carbide cluster. Under the same experimental conditions, [Ni10(C2)(CO)16]2âreacts with Na/naphtalene yielding a mixture of the previously reported [Ni11(C2)(CO)15]4âand [Ni12(C2)(CO)16]4âmono-acetylide tetra-anions. The oxidation reactions of both [Ni9C(CO)17]2âand [Ni10(C2)(CO)16]2â, carried out with miscellaneous reagents, e.g., [C7H7][BF4], [Cp2Fe][PF6], AgNO3, are more complicated and less selective, leading to mixtures of products, among which the previously reported [Ni8C(CO)16]2â, [Ni16(C2)2(CO)23]4â, [Ni38C6(CO)42]6âand [Ni32C6(CO)36]6âspecies have been identified. Interestingly, oxidation of [Ni10(C2)(CO)16]2âwith Pd(Et2S)2Cl2affords the new tetra-acetylide [Ni22(C2)4(CO)28(Et2S)]2â, even if in low yields. The new species [Ni12C(CO)18]4âand [Ni22(C2)4(CO)28(Et2S)]2âhave been structurally characterized by means of single crystal X-ray diffraction. Electrochemical and spectroelectrochemical studies have been performed on [Ni12C(CO)18]4â. This compound can be electrochemically oxidized and reduced reversibly affording [Ni12C(CO)18]3âand [Ni12C(CO)18]5â, respectively. The same species can be obtained by chemical methods but, due to their limited stability during work-up, it has not been possible to isolate them