Expanded polycationic mercury-chalcogen networks in the layered compounds Hg3E2[MX6] (E = S, Se; M = Zr, Hf, X = Cl, Br)

The reactions of HgE (E= S, Se) with Hgchi(2), and MX4 (M = Zr, Hf, X = Cl, Br) in evacuated glass ampoules lead to a series of isotypic compounds of the general formula Hg3E2[MX6] in the form of colorless (X = Cl) and light-yellow (X = Br) air-sensitive crystals. The crystal structures of Hg3S2[ZrCl6] (I), Hg3S2[HfCl6] (II), Hg3Se2[ZrCl6] (III), Hg3Se2[ZrCl6] (IV), Hg3S2[ZrBr6] (V), and Hg3Se2[ZrBr6] (VI) were refined based on single-crystal data. All compounds crystallize in the monoclinic space group P2(1)/a with the lattice parameters a = 662.18(2) pm, b = 734.97(3) pm, c = 1290.83(5) pm, beta = 91.755(2)degrees for (1) and and a = 701.97(3) pm, b = 756.79(3) pm, c = 1350.99(6) pm, beta = 92.164(3)degrees for (VI). The structures are built of (Hg3E2)(2+) layers stacked perpendicular to the c-axis. The polycationic layers consist of two-dimensionally linked 12-membered Hg6E6 rings in the chair conformation with linear coordinated Hg and trigonal pyramidal coordinated chalcogen atoms. Almost regular octahedral [MX6](2-) ions are embedded between the layers. This arrangement is closely related to the structure of Hg3S2[SiF6], which represents a higher symmetric congener. The structure relation is discussed using the supergroup-subgroup relation between space groups. (C) 2002 Elsevier Science (USA). All rights reserved.