Systematic synthesis of hexanuclear phosphido-bridged osmium clusters; crystal and molecular structure of [Os₆(μ-H)(CO)₂₂(μ-PH₂)]

The phosphide-bridged cluster [Os₆(μ-H)(CO)₂₂(μ-PH₂)] and the corresponding phosphinidene-bridged cluster [Os₆(μ-H)₂(CO)₂₁(μ-PH)] have been prepared from the reaction of [Os₃(CO)₁₁(PH₃)] with [Os₃(CO)₁₁(NCMe)] in toluene. In a similar reaction, [Os₆(μ-H)(CO)₂₁(NCMe)(μ-PH₂)] has been prepared from the reaction of [Os₃(CO)₁₁(PH₃)] with [Os₃(CO)₁₀(NCMe)₂]. The two Os₆ clusters have been fully characterized on the basis of their spectroscopic data and, in the case of [Os₆(μ-H)(CO)₂₂(μ-PH₂)], by single-crystal X-ray analysis. In both compounds, two Os₃ triangles are linked by a PH₂ group which is terminally bound to each triangle. Thermolysis of [Os₆(μ-H)(CO)₂₂(μ-PH₂)] and [Os₆(μ-H)(CO)₂₁(NCMe)(μ-PH₂)] leads to the formation of [Os₆(μ₆-P)(CO)₁₈]^- and [Os₆(μ-H)(μ₆-P)(CO)₁₈], respectively.