Metal-metal interactions in chain compounds of gold(I): syntheses and crystal structures of chlorotetrahydrothiophenegold(I), bromotetrahydrothiophenegold(I) and iodotetrahydroselenophenegold(I)

Abstract 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 Kα, \ gl = 0.7107 A) are: [Au(C 4 H 8 S)Cl], orthorhombic, Pmc 2 v , Z = 4, a = 6.540(1), b = 8.192(1), c = 12.794(3) A and V = 685.5(2) A 3 ; [Au(C 4 H 8 S)Br], orthorhombic, Pmc 2 v , Z = 4, a =6.564(1), b = 8.328(2), c = 13.229(4) A and V = 723.1(2) A 3 ; [Au(C 4 H 8 Se)I], orthorhombic, Pc 2 1 n , Z = 8, a = 8.286(2), b = 11.552(3), c = 16.204(6) A and V = 1551.0(5) A 3 . Full matrix least-squares refinements using reflections obeying I > 2 σ ( 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(C 4 H 8 S)Cl] and [Au(C 4 H 8 S)Br] are isostructural and comprise linear, neutral complexes, [Au(C 4 H 8 S)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) A and Au-Au-Au angles of 159.30(6)° and 156.29(8)° for the chloro and bromo complexes, respectively. The Au-S distances are in the range 2.26-2.28 A for both compounds, indicating that the difference in trans -influence of Cl and Br on the Au-S distance is negligible. [Au(C 4 H 8 Se)I] is composed of linear complexes, [Au(C 4 H 8 Se) 2 ] + and [AuI 2 ] − , which alternate in infinite zigzag chains running along b , with Au-Au distances of 2.987(2) and 3.001(2) A and with Au-Au-Au angles of 160.89(4)° and 156.35(4)°. The Au-I and Au-Se distances are in the ranges 2.569(2)–2.571(2) and 2.430(3)–2.436(3) A, 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 A, with a frequency maximum at 3.2–3.4 A.