The influence of molecular hydrogen on the reaction between [Ru3(CO)12] and [Ni2(η-C5H5)(C2Ph2)]. Synthesis and crystal structure of the new heteropentametallic cluster [Ni2Ru3(η-C5H5)2(CO)6(µ-CO)2(µ4,η2-C2Ph2)]

Abstract

The effect of the presence of H₂ on the reaction of [Ru₃(CO)₁₂] with [Ni₂(η-C₅H₅)₂(C₂Ph₂)] has been investigated; under these conditions the new square-pyramidal heteropentametallic cluster [Ni₂Ru₃(η-C₅H₅)₂(CO)₆(µ-CO)₂(µ₄,η₂-C₂Ph₂)] is obtained in 6–10% yield, in conjunction with other heterometallic compounds. This complex has been characterized by spectroscopy and its crystal structure determined by X-ray methods. It crystallizes in the monoclinic space group P2₁/n, with a= 16.459(8), b= 20.280(9), c= 9.423(6)Å, β= 105.67(3)° and Z= 4. The structure has been solved by direct and Fourier methods and refined by full-matrix least squares to R= 0.040 for 3 114 observed reflections. The cluster adopts a square-pyramidal arrangement with alternating Ru and Ni atoms in the basal plane; the diphenylacetylene is co-ordinated to these basal metal atoms, through σ bonds to the Ni and π bonds to the Ru atoms. A comparison of this complex, which is the first example of a heteropentametallic alkyne-substituted cluster having a square-pyramidal arrangement, with other homo- and hetero-metallic clusters is made on the basis of isolobality.