Synthesis and Structure of Os5(μ-Cl)2(CO)16(CNBut)2: A Cluster with a “Hook” Arrangement of Metal Atoms

Os5(μ-X)2(CO)16(L)2 (X=Cl, 1, Br; L=CNBut) clusters have been prepared by the reaction of Os3(μ-X)2(CO)10 with Os(CO)4(L) at a 1:2 molar ratio in solution at 60°C. The crystal structure of the chloro compound reveals that the Os3(μ-Cl)2 fragment present in the precursory cluster is maintained in 1 with a coordination site cis to the Cl ligands occupied by the unusual Os(CO)4Os(CO)3(L)2 unit. The resulting “hook” arrangement of the Os5 skeleton has not been observed previously. The OsOs lengths are in the range 2.8384(6)–2.8999(6)Å. The OsOs bonds associated with the pendant fragment are both considered dative bonds.