Solid State Supramolecular Complexes [Hg₆As₄](CuX₃)₂ (X = Cl, Br): One-Dimensional Helical Guest in a Three-Dimensional Host Framework

Abstract

Two new supramolecular complexes, [Hg₆As₄](CuBr₃)₂ (1) and [Hg₆As₄](CuCl₃)₂ (2), have been synthesized and their crystal structures have been determined. Compound 1 crystallizes in the monoclinic system, space group I2/a (No. 15), with the unit cell dimensions a = 14.884(3), b = 9.358(2), c = 20.413(4) Å, β=92.88(3)°, and Z = 6. The crystal structure is comprised of the three-dimensional $_{\infty}^{3}$[Hg₆As₄]⁴⁺ polycationic framework hosting one-dimensional 6-step helical $_{\infty}^{1}$(CuBr$_{3})^{2-}$ guest chains built of the [CuBr₄] tetrahedra sharing two of their vertexes. The complex 2 exhibits a distorted variant of the same type of crystal structure (space group I2/a, a = 14.690(1), b = 9.1851(7), c = 20.285(1)  Å, β=92.170(1), and Z = 6) that is characterized by a multifarious positioning of the guest anions in the cavities of the perfectly ordered $_{\infty}^{3}$[Hg₆As₄]⁴⁺ host framework. Structures of the title supramolecular assemblies and the previously reported silver-containing analogue [Hg₆As₄](AgCl₃)₂ are discussed taking into account the principles of host–guest complementarity.