Crystal structure of [μ-1κ(2)C(1),C(4):2(1,2,3,4-η)-1,2,3,4-tetra-phenyl-buta-1,3-diene-1,4-di-yl]bis-(tri-carbonyl-osmium)(Os-Os).

In the title complex C(34)H(20)O(6)Os(2) or (μ-η(4)-C(4)Ph(4))Os(2)(CO)(6), one Os atom is part of a metalla-cyclo-penta-diene ring, while the second Os atom is π-bonded to the organic portion of this ring. The distance of 2.7494†(2)†à between the two Os atoms is typical of an Os-Os single bond. Three carbonyl ligands are attached to each Os atom and these six carbonyls adopt an eclipsed conformation. There are no bridging or semibridging CO groups. Two carbonyl ligands and all four phenyl groups are disordered over two slightly different positions for which each atom in the minor components is displaced less than 1†à from the corresponding atom in the major components. The refined occupancies of the major com-ponents of the carbonyl ligands are 0.568†(16) and 0.625†(13), while those for the phenyl rings are 0.50†(3), 0.510†(12), 0.519†(18), and 0.568†(12).