METAL-METAL INTERACTIONS IN CHAIN COMPOUNDS OF GOLD(I) - SYNTHESES AND CRYSTAL-STRUCTURES OF CHLOROTETRAHYDROTHIOPHENEGOLD(I), BROMOTETRAHYDROTHIOPHENEGOLD(I) AND IODOTETRAHYDROSELENOPHENEGOLD(I)

The crystal structures of the title compounds have been determined from X-ray intensity data collected at 200 K with a CAD 4 diffractometer. Crystal data at 200 K (Mo Ka, lambdaBAR = 0.7107 angstrom) are: [Au(C4H8S)Cl], orthorhombic, Pmc2(1) Z = 4, a = 6.540(1), b = 8.192(1), c = 12.794(3) angstrom and V = 685.5(2) angstrom3 ; [Au(C4H8S)Br], orthorhombic, Pmc2(1), Z = 4, a = 6.564(1), b = 8.328(2), c = 13.229(4) angstrom and V = 723.1(2) angstrom; [Au(C4H8Se)I], orthorbombic, Pc2(1)n, Z = 8, a = 8.286(2), b = 11.552(3), c = 16.204(6) angstrom and V = 1551.0(5) angstrom. Full matrix least-squares refinements using reflections obeying I > 2sigma(I) converged to R = 0.053 (652 reflections), R = 0.067 (656 reflections) and R = 0.049 (1453 reflections) for the chloro, bromo and iodo compounds, respectively. [Au(C4H8S)Cl] and [Au(C4H8S)Br] are isostructural and comprise linear, neutral complexes, [Au(C4H8S)X], which are stacked in a staggered conformation forming infinite arrays of gold atoms running along a with gold-gold distances of 3.324(1) and 3.353(1) angstrom and Au-Au-Au angles of 159.30(6)-degrees and 156.29(8)-degrees for the chloro and bromo complexes, respectively. The Au-S distances are in the range 2.26-2.28 angstrom for both compounds, indicating that the difference in trans-influence of Cl and Br on the Au-S distance is negligible. [Au(C4H8Se)I] is composed of linear complexes, [Au(C4H8Se)2]+ and [AuI2]-, which alternate in infinite zigzag chains running along b, with Au-Au distances of 2.987(2) and 3.001(2) angstrom and with Au-Au-Au angles of 160.89(4)-degrees and 156.35(4)-degrees. The Au-I and Au-Se distances are in the ranges 2.569(2)-2.571(2) and 2.430(3)-2.436(3) angstrom, respectively. Since there are no ligand bridges between the gold atoms in any of these compounds, the fairly short gold-gold distances indicate metal-metal bonding. A survey of short Au-Au interactions, not supported by ligand bridges, shows a wide range of distances, 2.97 to 3.78 angstrom, with a frequency maximum at 3.2-3.4 angstrom.