Synthesis and structural characterisation of heptaosmium alkyne clusters

Abstract

Reaction of the cluster [Os₇H₂(CO)₂₀]1 with Me₂C₂ in toluene at 90–100 °C gives [Os₇(CO)₁₉(Me₂C₂)]2 in moderate yield. The more reactive species [Os₇H₂(CO)₁₉(MeCN)]3 reacts with the same alkyne at room temperature to yield 2 together with [Os₇H₂(CO)₁₉(Me₂C₂)]4. Cluster 4 is also the only product from the reaction of [Os₆(CO)₁₅(Me₂C₂)(MeCN)]5 with [OsH₂(CO)₄]. On further heating with excess of Me₂C₂, cluster 2 reacts to produce the species [Os₇(CO)₁₆(Me₂C₂)₃]6. On prolonged heating, cluster 2 loses CO to form [Os₇(CO)₁₈(µ₃-CMe)₂]7. Compounds 2, 4 and 6 have been characterised on the basis of their ¹H NMR, IR, and electron-impact mass spectral data. The molecular structure of cluster 2 has been determined by a single-crystal X-ray diffraction study.