Dicarboxylato ligands in osmium carbonyl sawhorse clusters: Chelating vs. bridging

Microwave heating is used to synthesize two diosmium complexes with one chelating dicarboxylato ligand, four tetraosmium complexes with two bridging dicarboxylato ligands, and one hexaosmium complex with three bridging dicarboxylato ligands. Each one of these seven complexes contains one or more osmium carbonyl sawhorse units.142