The growth of higher nuclearity carbonyl clusters of ruthenium and osmium.

• Methods for the synthesis of high nuclearity carbonyl clusters of ruthenium and osmium. • Analysis of the structures of high nuclearity carbonyl clusters of ruthenium and osmium. • Osmium and ruthenium clusters with nuclearities greater than 6 metals. • Linked higher nuclearity clusters. • Mixed-metal clusters containing ruthenium or osmium. In this review the synthetic and structural chemistry of osmium and ruthenium clusters is described with emphasis on the studies carried out during the 1980s and 1990s when research in the area was prolific. The methods of cluster synthesis are discussed as are the techniques used to characterise the complexes. The electron counting methods that are used to predict and rationalise the cluster structures are highlighted. Emphasis is placed on the synthetic methods used to build high nuclearity carbonyl clusters of osmium and ruthenium, namely vacuum pyrolysis, the linking of cluster fragments with bridging ligands, and the development of methodologies used to build higher nuclearity mixed-metal clusters. [ABSTRACT FROM AUTHOR]