Crystal structure of the synthetic analog of radtkeite Hg₃S₂Cl_1.00I_1.00

Abstract

The results of structural studies of the synthetic analog of the radtkeite mineral Hg₃S₂Cl_1.00I_1.00 are analyzed. The crystal structure of the compound has been refined; the unit cell parameters are a _m = 16.827(4) Å, b _m = 9.117(1) Å, c _m = 13.165(5) Å, β = 130.17(2)°, V = 1543.3(8) ų, space group C2/m, Z = 8, R = 0.0527. A possible transition a ^′₀ = a _m; b ^′₀ = a _m + 2c _m; c ^′₀ = −b _m to the pseudo-orthorhombic F cell previously determined for radtkeite, where one of the angles (γ ^′₀ ) is slightly different from 90° (89.55°), has been found. Each sulfur atom in the structure is bonded to three mercury atoms, forming SHg₃ umbrellas with distances 2.240(6) Å–2.474(8) Å and angles HgSHg 94.7(2)°–102.9(2)°. The SHg₃ fragments are linked through Hg vertices to form corrugated [Hg₁₂S₈]∞∞ layers. The halogen atoms lie inside and between the [Hg₁₂S₈]∞∞ layers; the distances are Hg-Cl and Hg-I 2.783(7) Å, 2.961(7) Å, and 3.083(4) Å–3.311(3) Å, respectively.