Two tetracobalt cluster complexes:: Preparation and molecular structures of Co4(μ-dppm)2(μ-CO)3(CO)5 and Co4(μ-CO)3(CO)6(η-C6H6)

The crystal and molecular structures of the title complexes (1) and (2) are described. Each contains a Co-4 tetrahedron, one face of which is edge-bridged by three mu -CO ligands. In (1), a pair of mutually orthogonal Co-Co bonds are bridged by the two dppm (dppm = bis(diphenylphosphino)methane) ligands. The structure of the benzene complex was determined at 153 and 300 K; as with other arene-Co-4 clusters, the eta (6)-benzene ligand sits on the apical (i.e. non-CO-bridged) Co atom.