Cadmium-substitution promoted by nucleophilic attack of [Ni30C4(CO)34(CdX)2]6− (X = Cl, Br, I) carbido carbonyl clusters: Synthesis and characterization of the new [H7−nNi32C4(CO)36(CdX)]n− (X = Cl, Br, I; n = 5, 6, 7) polycarbide

The reaction of [Ni9C(CO)17]2− with CdX2 · xH2O (X = Cl, Br, I) affords the tetra-carbide carbonyl clusters [H6−nNi30C4(CO)34(CdX)2]n− (n = 3–6; X = Cl, Br, I), which are transformed into the closely related [H7−nNi32C4(CO)36(CdX)]n− (n = 5, 6, 7; X = Cl, Br, I) by reaction with OH− or X− ions. A detailed crystal analysis clearly indicates that the latter is actually obtained in mixture with [H7−nNi31C4(CO)37(CdX)]n− and [H7−nNi33C4(CO)37(CdX)]n−, which differ only by the presence or the absence of Ni(CO) fragments. The above mixture can be considered to represent a fully characterized molecular example of “mono-dispersed colloids” of ligand-protected metal nanoparticles.