Poly{guanidinium bis[dichloromercury(II)]-μ4-chloro}

Abstract

Both the [C(NH2)3]+ cations and the [Hg2Cl5]− anions of the title compound occupy special positions on two different twofold axes, one passing through the central Cl atom of the anion (along [100]), the other along a C—N bond of the cation (along [010]). The coordination polyhedron around the Hg atom can be described as a distorted octahedron of six Cl atoms, with two short [2.306 (5) and 2.322 (4) Å], two long [2.905 (7) and 2.906 (7) Å] and two very long [3.271 (6) and 3.344 (6) Å] Hg—Cl distances. In the crystal structure, there are alternate layers of cations and polyanions. Taking the very long Hg—Cl contacts into account, the polyanions are built of Hg2Cl5− units (which can be described as two HgCl2 fragments connected via a chlorine anion), interconnected through the common square-planar coordinated Cl atom. Two factors act to stabilize the structure of the crystal, i.e. the electrostatic interaction between the adjacent layers and the network of N—H⋯Cl hydrogen bonds.