Gold(I) dimers. The synthesis and reactions of [ tert -BuC≡CAu(dmpm—P)], and the crystal and molecular structures of [Au 2 (µ-dmpm) 2 ]X 2 •2H 2 O, X = Cl, I

• Published in: Canadian journal of chemistry 1988-12, Vol.66 (12), p.3176-3183
• Main Authors: Payne, N. C., Puddephatt, R. J., Ravindranath, R., Treurnicht, I.
• Format: Article
• Language: English
• ISSN: 0008-4042; 1480-3291
• DOI: 10.1139/v88-491

Acetylide complexes of formula [tert-BuC≡CAu(R 2 PCH 2 PR 2 )], R = CH 3 (6a) and C 6 H 5 (6b), have been prepared, and characterized by spectroscopic methods. These complexes undergo a fluxional process involving a three-coordinate Au(I) centre. Complex 6a dimerizes by a first-order process in chlorinated solvents, with substitution of the acetylide ligand by chloride ion, to form [Au 2 (µ-dmpm) 2 ]Cl 2 •2H 2 O (7a). The crystal and molecular structures of 7a and the iodide salt 7b have been determined by single crystal X-ray diffraction methods. Both crystallize in the triclinic space group [Formula: see text] with Z = 1; unit cell dimensions are a = 7.962(1), b = 9.987(1), c = 7.895(1) Å, α = 90.11, β = 109.13(1), and γ = 112.84(1)° for 7a; a = 8.243(1), b = 9.057(1), c = 8.167(1) Å, α = 90.23, β = 110.33(1), and γ = 89.92(1)° for 7b. The analyses refined to final agreement factors on F of R = 0.035 based on 3225 unique reflections with I > 3σ (I) for 7a, and R = 0.030 based on 2971 unique reflections with I > 3σ(I) for 7b. The structures are closely related, with the cations containing an eight-membered centrosymmetric ring formed by the Au(I) centres and the bridging dmpm ligands. The Au … Au′ distances are 3.014(1) and 3.019(1) Å in 7a and 7b, respectively. In the solid state, the halide ions bridge the two Au centres, and, together with the water molecules, form a network of hydrogen bonds running at an angle of 104° to the eight-membered Au 2 P 4 C 2 rings.