Heteronuclear cluster compounds

Abstract
Several designed syntheses have been developed for heteronuclear organometallic cluster compounds. They involve step-by-step construction, fragment combination and metal exchange. The compounds obtained permit the study of the physical phenomena of electron distribution and chirality in the cluster frameworks. Prominent chemical phenomena are the weakness of some metal-metal bonds, the unsaturated nature of some clusters, and polarity due to heteronuclearity. They permit the study of basic cluster reactions like the unfolding of the clusters with nucleophiles, the addition of substrates without gross changes in the cluster framework and without ligand substitution, the capping of clusters by suitable ligands, and the reaction of different substrates at different locations in the cluster core.