Synthesis of 1,3-diaryltriazenido triruthenium and triosmium clusters: crystal structures of [Ru3(µ-H)(CO)10(µ-C6F5NNNC6F5)] and [Os3(CO)11Cl(η2-C6F5NNNC6F5)]

Abstract

New clusters [Ru₃(µ-H)(CO)₁₀(µ-RNNNR)](R =p-C₆F₄X; X = F 1, Br 2, I 3 or H 4) were obtained from reactions of RNNNHR with [Ru₃(CO)₁₂] in toluene at 80 °C under vacuum, while the linear triosmium clusters [Os₃(CO)₁₁Cl(η²-RNNNR)](R =p-C₆F₄X; X = F 5, Br 6, I 7 or H 8) were obtained from RNNNHR with [Os₃(CO)₁₁(NCMe)] in CH₂Cl₂ at 60 °C under vacuum. The crystal structures of [Ru₃(µ-H)(CO)₁₀(µ-C₆F₅NNNC₆F₅)]1 and [Os₃(CO)₁₁Cl(η²-C₆F₅NNNC₆F₅)]5 have been determined by single-crystal X-ray crystallography. The structure of 1 shows that the triazenide ligand bridges one Ru–Ru vector in the cluster at axial sites and forms a five-membered ring with π delocalization over the whole system. A hydride ligand was located which bridges another Ru–Ru vector equatorially and displays interesting fluxionality in solution. The chloride ligand in complex 5 co-ordinates equatorially at the first Os atom, while the triazenide occupies an axial and an equatorial site on the third Os in the linear cluster and forms a four-membered ring with π delocalization over the whole system. The linear cluster [Os₃H(CO)₁₁(η²-C₆F₅NNNC₆F₅)], precursor of 5, was also obtained. Carbon-13 NMR studies of this cluster and the mechanism of its formation are reported.