SYNTHESIS AND STRUCTURE OF THE NEW GOLD POLYTELLURIDE ANION [AU2TE12]4-

The ethylenediamine (en) extraction of an alloy of nominal composition KAuBiTe3 or K4Au2Te12 followed by treatment with Et4NBr in methanol gave (Et4N)4[Au2Te12] (1) in 15% yield. Dark red crystals of 1 crystallize in the monoclinic space group P2(1)/c (No. 14) with unit cell dimensions a = 14.948(2) angstrom, b = 10.168(2) angstrom, c = 20.591(4) angstrom, beta = 108.15 (1)degrees, V = 2973.7(7) angstrom3, Z = 2, and d(calc) = 2.732 g cm-3 with R (R(w)) = 0.076 (0.069) for 1914 reflections with 2theta < 50-degrees and I greater-than-or-equal-to 3sigma(I). The X-ray diffraction data revealed a novel dimeric [Au2Te12]4- anion which consists of square planar Au3+ coordinated by eta3-Te-5(4-) ligand forming [AuTe5]- moieties, two of which are bridged together by a eta2-Te-2(2-) ligand.