Molecular nickel poly-carbide carbonyl nanoclusters: The octa-carbide [HNi42C8(CO)44(CuCl)]7- and the deca-carbide [Ni45C10(CO)46]6-

The reaction of [Ni10(C2) (CO)16]2- with CuCl in thf affords [Ni45C10(CO)46]6- as the major product. This represents the first deca-carbide carbonyl cluster and this is the highest number of C-atoms found in a molecular cluster. Besides, the new octa-carbide [HNi42C8(CO)44(CuCl)]7- and the previously reported tetra-carbide [Ni34+xC4(CO)38+x]6- (x = 0,1) have been obtained as side-products. Whilst studying the reactions of miscellaneous Ni carbide clusters with Cu(I) salts in the search for a better synthesis of [HNi42C8(CO)44(CuCl)]7-, the homoleptic [Ni32+xC6(CO)36+x]6- (x = 0-2) and the heteroleptic [Ni38C6(CO)36(MeCN)6(CuMeCN)2x]2- clusters have been isolated in low yields. By analysing the Ni carbide clusters herein reported as well as those previously described in the literature, it results that they are built-up starting from four fundamental building blocks: octahedral Oh-Ni6C, trigonal prismatic TP-Ni6C, capped trigonal prismatic cTP-Ni7C and square anti-prismatic SA-Ni8C. These may be joined into larger NixCy metal-carbide frameworks by sharing vertices, edges or faces. Even though infinite combinations are possible, some NixCy motives are common to two or more clusters, envisioning a possible rationale behind their building-up.