Gold Inorganic Rings Based on Polychalcogenide Chains

Abstract

The reaction of AuCN with Se_x ^2- and Te_x ^2- in dimethylformamide in the presence of organic cations forms complexes with ring structures such as (Ph₄P)₂[Au₂Se₅] (I), (Ph₄P)₂[Au₂Se₆] (II), (Ph₃P N P Ph₃)2 - K₂[Au₄Te₄]·2DMF (III). The reaction of AuCl₃ with Te^2- yielded (Ph₄P)₂[Au₂(Te₂)₂] (IV). (I) crystallizes in the triclinic space group P-1 with a=10.381(4) Å, b=11.002(5) Å, c=21.181(9) Å, α = 75.50(4)°, β = 74.74(3)°, γ=81.40(4)°, V=2250 ų (-93 °C). (II) crystallizes in the monoclinic space group C2/c with a=28.409(7) Å, b=10.97(1) Å, c=19.762(5) Å, β=130.49(1)°, V=4680 ų (-93 °C). (III) crystallizes in the orthorhombic space group Pbcn with a=29.90(2)Å, b=17.39(2)Å, c=17.707(8)Å, V=9206ų (23 °C). (IV) crystallizes in the triclinic space group P-1 with a=10.526(3)Å, b=11.237(2)Å, b=11.237(2)Å, α=103.03(2)°, β=106.95(3)°, γ=81.66(2)°, V=1148 A³ (-95 °C). Single-crystal X-ray diffraction studies of (I) and (11) show that both compounds possess the same structural feature. Two linearly-coordinated Au(I) atoms interact with each other at 3.004 Å in (I) and 3.132Å in (II) with a bridging Se₂ ^2- unit on one side and a bridging triselenide Se3^2- ligand (for II) on the other, forming respectively seven and eight membered rings each containing two gold atoms. The structure of (III) consists of a distorted square where the Te atoms occupy the corners and the Auatoms lie in the center of the square's edges. Ionic interactions between the Au and K atoms result in a one-dimensional structure. The structure of (IV) is similar to those of (I) and (11) except two Te₂ ^2- ligands are involved.