Reactivity of triosmium clusters with 3,4-dimethyl-1-phenylphosphole and cyanoethyldi-tert-butylphosphine ligands: X-ray crystal structures of [Os(CO)(μ-OH)(μ-H)(η-PhPCHMe)] and [Os(CO)(η-BuPCHCN)]

Reaction of [Os(μ-H)(CO)] with 3,4-dimethyl-1-phenylphosphole in refluxing cyclohexane affords two substituted triosmium clusters: [Os(CO)(μ-H)(μ:η:η:η-PhPCHMe)] and [Os(CO)(H)(μ-η:η-PhPCHMe)] , of which cluster exhibits two chromatographically non-separable isomeric forms attributed to terminal and bridging coordination of the hydride ligand, respectively. When this reaction is performed in refluxing THF, the only product is the cluster [Os(CO)(μ-OH)(μ-H)(η-PhPCHMe)] . Crystallographic information obtained for cluster shows the phosphole ligand occupying an equatorial position, as expected, while the OH group is asymmetrically bridging unlike previously reported similar compounds. Additionally, interaction of the labile cluster [Os(CO)(CHCN)] with cyanoethyldi-tert-butylphosphine in dichloromethane at room temperature was found to give [Os(CO)(η-BuPCHCN)] as the only product; its crystallographic characterization shows that the phosphine ligand coordinates by means of the phosphorus atom in an equatorial fashion, analogous to compound .