Cage Opening of a Carborane Ligand by Metal Cluster Complexes

The reaction of Os-3(CO)(10)(NCMe)(2) with closo-o-C2B10H10 has yielded two interconvertible isomers Os-3(CO)(9)((3)-4,5,9-C2B10H8)(-H)(2) (1a) and Os-3(CO)(9)((3)-3,4,8-C2B10H8)(-H)(2) (1b) formed by the loss of the two NCMe ligands and one CO ligand from the Os-3 cluster. Two BH bonds of the o-C2B10H10 were activated in its addition to the osmium cluster. A second triosmium cluster was added to the 1a/1b mixture to yield the complex Os-3(CO)(9)(-H)(2)((3)-4,5,9-(3)-7,11,12-C2B10H7)Os-3(CO)(9)(-H)(3) (2) that contains two triosmium triangles attached to the same carborane cage. When heated, 2 was transformed to the complex Os-3(CO)(9)(-H)((3)-3,4,8-(3)-7,11,12-C2B10H8)Os-3(CO)(9)(-H) (3) by a novel opening of the carborane cage with loss of H-2.