The heteronuclear cluster chemistry of the group 1B metals. Part 7. Synthesis and gold-197 Mössbauer spectra of the mixed-metal cluster compounds [Au2Ru4(µ3-H)(µ-H){µ-Ph2E(CH2)nE′Ph2}(CO)12](n= 1 or 2, E = E′= As or E = As, E′= P; n= 2, E = E′= P). X-Ray crystal structure of [Au2Ru4(µ3-H)(µ-H)(µ-Ph2AsCH2PPh2)(CO)12]

Abstract

Treatment of acetone solutions of the salt [N(PPh₃)₂]₂[Ru₄(µ-H)₂(CO)₁₂] with a dichloromethane solution of the appropriate complex [Au₂{µ-Ph₂E(CH₂)_nE′Ph₂}Cl₂], in the presence of TlPF₆, affords the mixed-metal cluster compounds [Au₂Ru₄(µ₃-H)(µ-H){µ-Ph₂E(CH₂)_nE′Ph₂}(CO)₁₂][E = E′= P, n= 2 (3); E = E′= As, n= 1 (4) or 2 (5); E = As, E′= P, n= 1 (6) or 2 (7)] in ca. 50–70% yield. An X-ray diffraction study on [Au₂Ru₄(µ₃-H)(µ-H)(µ-Ph₂AsCH₂PPh₂)(CO)₁₂](6) revealed a metal-core structure consisting of a square-based pyramid, defined by two Au atoms and two Ru atoms in the basal plane and a Ru atom at the apex, with the Ru₃ face of this Au₂Ru₃ unit capped by a Ru atom [Au–Au 2.832(4), Au–Ru 2.689(4)–2.846(4), and Ru–Ru 2.792(5)–3.029(5)Å]. The asymmetrical bidentate ligand bridges the two Au atoms, one hydrido ligand caps a Ru₃ face and one bridges a Ru–Ru edge of the metal framework, and each Ru atom is ligated by three terminal CO groups. The ¹⁹⁷Au Mössbauer spectra of clusters (3)–(7) are reported. These data suggest that [Au₂Ru₄(µ₃-H)(µ-H)(µ-Ph₂AsCH₂AsPh₂)(CO)₁₂](4) exhibits a similar skeletal geometry to that of (6), whereas (3), (5), and (7) all adopt a capped trigonal-bipyramidal metal-core structure, with the two gold atoms occupying geometrically distinct sites.