Formation of new halogeno mixed-metal clusters by oxidative addition of triphenylphosphinegold(I) halides to [Ru5C(CO)15]: crystal and molecular structures of [Ru5C(CO)15{µ-Au(PPh3)}Cl] and [Ru5C(CO)14{µ-Au(PPh3)}(µ-Br)]

Abstract

In CH₂Cl₂ the compound [Ru₅C(CO)₁₅] reacts with [Au(PPh₃)X](X = Cl or Br) to form [Ru₅C(CO)₁₅{µ-Au(PPh₃)}X] which loses one mole of CO to form [Ru₅C(CO)₁₄{µ-Au(PPh₃)}(µ-X)], where X functions as a three-electron donor. The crystal structures of [Ru₅C(CO)₁₅{µ-Au(PPh₃)}Cl] and [Ru₅C(CO)₁₄{µ-Au(PPh₃)}(µ-Br)] are reported. The complex [Ru₅C(CO)₁₅{µ-Au(PPh₃)}Cl] crystallizes in the triclinic space group P with a= 15.333(3), b= 15.865(3), c=18.813(7)Å, α= 84.29(4), β= 84.41 (4), γ= 61.88(2)°, and Z= 4 with two distinct molecules per asymmetric unit. For 5 487 reflections the structure refined to R 0.0703 and R′ 0.0539. The molecule contains a bridged butterfly configuration of ruthenium atoms (seven Ru–Ru bonds) with the gold atom bridging the butterfly ‘hinge’ bond and the chloride attached terminally to the ruthenium that spans the wing tips of the butterfly. All ruthenium atoms remain bonded to the carbide atom, but the gold and chlorine show no interaction with the carbide. For [Ru₅C(CO)₁₄{µ-Au(PPh₃)}(µ-Br)] the space group is monoclinic, P2₁/c, with a= 8.967(1), b= 29.767(7), c= 15.010(3)Å, β= 92.16(1)°, and Z= 4. For 2 950 reflections, the refinement converged with R 0.0432 and R′ 0.0434. The molecule is best described as a distorted square pyramid of ruthenium atoms in which one apical to basal Ru–Ru bond is replaced by a bridging three-electron donating bromine. The complex is derived from the 15 carbonyl complex by displacement of one of the hinge carbonyls by the halide.