Cage Opening of a Carborane Ligand by Metal Cluster Complexes

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