Toward rational construction of gold, gold-silver, and gold-mercury string complexes:: Syntheses, structures, and properties of [Au(Tab)2]2L2 (L = I and PF6), {[(Tab)2M][Au(CN)2]}2 (M = Au and Ag), and {[Hg(Tab) 2][Au(CN)2]2} [Tab=4-(trimethylammonio)benzenethiolate]

The reaction of Aul with 2 equiv of TabHPF(6) [TabH = 4-(trimethylammonio) benzenethiol] in the presence of excess Et3N in dimethylformamide (DMF)/MeOH afforded a binuclear gold(I) complex [Au(Tab)(2)](2)I-2 center dot 2H(2)O (1). Anion exchange of 1 with NH4PF6 in DMF gave rise to the more soluble complex [Au(Tab)(2)](2)(PF6)(2) (2). Treatment of 2 with K[Au-(CN)(2)] produced a tetranuclear gold(I) complex {[(Tab)(2)Au][Au(CN)(2)]}(2) (3). Analogous reactions of two known mononuclear complexes [Ag(Tab)(2)](PF6) (4) and [Hg(Tab)(2)](PF6)(2) (5) with 1 or 2 equiv of K[Au(CN)(2)] generated one Ag2Au2 complex {[(Tab)(2)Ag][Au(CN)(2)]}(2) (6) and one Au/Hg complex {[Hg(Tab)(2)][Au(CN)(2)](2)} (7), respectively. Compounds 1-3, 6, and 7 were fully characterized by elemental analysis, IR spectra, UV-vis spectra, H-1 NMR, and single-crystal X-ray crystallography. 1 and 2 have a similar [Au(Tab)(2)](2)(2+) dimeric structure in which the two [Au(Tab)(2)](+) cations are connected via one Au-Au aurophilic interaction. In the structure of 3 or 6, each of the two pairs of [M(Tab)(2)](+) cation and [Au(CN)(2)](-) anion is held together via ionic interactions to form a {[(Tab)(2)M][Au-(CN)(2)]} species (M = Au, 3; Ag, 6). Two such species are further connected by one Au - Au aurophilic bonding interaction to form an uncommon Au-4 or Ag2Au2 linear string structure with three ligand-unsupported metal-metal bonds. For 7, the [Hg(Tab)(2)](2+) dication and the [Au(CN)(2)](2)(2-) dianion are interconnected by the secondary Hg center dot center dot center dot N(CN) interactions to form a 1D chain structure. The thermal and luminescent properties of 1 - 3, 6, and 7 in solid state were also investigated.