Halide and chalcogenide clusters of the early transition metals

Abstract

In the last decade remarkable progress has been made in the cluster chemistry of the early transition elements. Earlier work on the metal halide cluster compounds of Nb, Ta, Mo, W and Re served to establish the promise and potential in this area. Now cluster chemistry has been extended to halides of Sc, Y, the lanthanides, Zr and Hf, as well as to oxides, sulphides and selenides of Nb, Ta, Mo and Re. After a brief survey of significant developments in these areas, attention is focused on results from recent work on Mo and W cluster compounds. The discussion includes syntheses, structures and properties of some novel halide clusters, but major emphasis is devoted to new ternary and quaternary molybdenum oxides prepared at high temperatures. Among these solid-state materials are found discrete cluster arrays (LiZn2Mo30 8, Zn3Mo30 8, and Ba114Mo80 16) and structures with extended metal-metal bonding (NaMo40 6, Ba5(Mo4Oe)8, Sc0 75Znj 25Mo40 7 and Ti0 5Zn4 5Mo40 7).