Synthesis, reactivity and structures of ruthenium carbonyl clusters with telluride and hydride ligands

Abstract

The reaction of [Cp* 2Nb(Te 2H)] ( 1) (Cp*=C 5Me 5) with [Ru 3(CO) 12] in boiling toluene gave [Ru 3(μ 2-H) 2(CO) 9(μ 3-Te)] ( 2), [Ru 6(μ 3-H)(CO) 15(μ 3-Te) 3][Cp* 2Nb(CO) 2] ( 3) and [Ru 5(μ 2-H)(CO) 14(μ 4-Te)][Cp* 2Nb(CO) 2] ( 4) along with already known [Ru 4(CO) 11(μ 4-Te) 2] ( 5). Complexes 2– 4 were analytically and spectroscopically characterized and X-ray diffraction analyses of 3 and 4 were carried out. The anion of 3 is built up of a triangular hexametallic core of C 3 v symmetry, in which the central Ru 3 triangle, being bridged by a μ 3-H ligand, is composed of three corner-linked Ru 3Te tetrahedra. The main structural feature of the anion of 4 is a Ru 5Te octahedron. The cations in 3 and 4 are known niobocenedicarbonyl species. The reaction of 2 with bis(diphenylphosphino)methane (dppm) gave [Ru 3(μ 2-H) 2(CO) 7(dppm)(μ 3-Te)] ( 6). Low temperature 1H-NMR spectroscopy and X-ray diffraction analysis show an unsymmetrical distribution of both hydride ligands over the triangular Ru 3 basis of the Ru 3Te tetrahedron. The reaction of 5 with dppm gave [Ru 3(CO) 7(dppm)(μ 3-Te) 2] ( 7) and known [Ru 4(CO) 9(dppm)(μ 4-Te) 2] ( 8). The crystal structure of 7 reveals a square pyramidal arrangement of the Ru 3Te 2 core. Electrochemical studies of 5 show this complex to be able to consume up to four electrons in reversible steps.