Syntheses and X-ray structures of mixed-metal gold phosphine clusters including an example having a highly asymmetric Re2Au2 skeleton

Article abstract of DOI:10.1016/S0020-1693(99)00209-1

This study describes the synthesis and single crystal X-ray characterization of three new heteronuclear gold clusters, i.e. (OC)₅Re-Re(CO)₄Au₂dppfe (1), Au₄Co₂(CO)₇(PPh₃)₃ (2), and [Au-Co(CO)₄]₂(cis-dpen) (3). They were synthesized from reaction of (AuCl)₂dppfe with NaRe(CO)₅ at room temperature, reaction of (PPh₃)AuCl with NaCo(CO)₄, and reaction of (AuCl)₂-(cis-dpen) with NaCo(CO)₄, respectively. Compound 1 crystallizes in the monoclinic space group P2₁/n with a = 15.331(7), b = 23.427(9), c = 13.621(6) A, β = 112.53(3)° and Z = 4. Compound 2 crystallizes in the triclinic space group P1 with a = 12.838(4), b = 22.406(6),_c = 11.759(4) A, a = 103.15(2), β = 117.06(2), γ = 82.78(2)°, and Z = 2. Compound 3 crystallizes in the triclinic space group P1 with a = 10.704(2), b = 17.437(3), c = 10.597(2) A, α = 96.73(2), β = 108.02(2), γ = 99.53(2)°, and Z = 2. In 1, two gold atoms in the Au₂dppfe group are bound to one Re atom in the Re₂(CO)₉ group. Thus, the total skeleton is highly asymmetric. The metal skeleton of 2 is composed from a butterfly-like Au₄ backbone with a capping Co(CO)₃ group and the terminal Co(CO)₄ group coordinated to one Au atom. Two gold atoms come close in 3 to cause intramolecular aurophilic interaction. Terminal Co(CO)₄ groups in 2 make an intermolecular pair in a head-to-tail manner in the crystal.