ZnBi alloy cluster breaks ground

Isolable metal clusters with more than a dozen atoms have become a hot research topic because they provide a segue from small cluster molecules to bulk metals. Better understanding of the structure and bonding of these species could lead to the controlled synthesis of molecular nanoparticles. In one of the latest advances in this area, Jose M. Goicoechea and Slavi C. Sevov of the University of Notre Dame report the synthesis of the 20-atom cluster [Zn₉Bi₁₁]^5- shown, where Zn is green and Bi is orange (Angew. Chem. Int. Ed., published online July 3, dx.doi.org/10.1002/anie.200601805). This compound is the first example of an "intermetalloid" cluster that incorporates two elements into the same cagelike lattice, Sevov notes. It was prepared by reacting K₅Bi₄ and a cryptand with diphenylzinc in ethylenediamine and isolated as the potassium cryptand salt. The cluster consists of a central zinc atom surrounded by eight zinc atoms and four bismuth atoms in an icosahedral arrangement, with the additional bismuth atoms capping seven of the 20 triangular faces of the icosahedron.