Axial and equatorial isomers in an isonitrile-substituted osmium-antimony cluster

Abstract

The reaction of tBuNC with the osmium-antimony cluster Os3(μ-H)(CO)10(μ-SbPh2) (1) proceeded via Os-Os bond cleavage to give HOs3(CO)10(μ-SbPh2)(CNBut) (2) in which the tBuNC ligand was added onto one of the osmium atoms bridged by the antimony. Cluster 2 exists in isomeric forms, where the tBuNC ligand occupies either an axial (a-2) or an equatorial (e-2) position with respect to the Os3Sb plane. In solution, e-2 was found to occur as a mixture of isomers in which the isonitrile was presumably either cis to the unique osmium or to the antimony.