Indene in a novel bonding mode in a carbonyl cluster: isolation, characterisation, and crystal and molecular structure of [HOs 4(CO) 9(C 9H 6)(C 9H 7)

Abstract

The reaction of [Os 3(CO) 12] with indene at 150°C under reflux affords the known compounds [H 2Os 3(CO) 9(C 9H 6)] ( 2) and [Os 4(CO) 12(C 9H 6)] ( 3). When the reaction temperature is increased to 170°C, the yield of 2 is greatly reduced, and a new tetraosmium cluster [HOs 4(CO) 9(C 9H 6)(C 9H 7)] ( 1) is isolated. An X-ray diffraction study of 1 has shown that one face of the Os 4 tetrahedron is capped by an indyne ligand coordinated in a μ 3-η 2-− bonding mode, while the indenyl ligand (C 9H 7) is coordinated to a single Os atom in a η 5 bonding mode through the five-membered ring.