CRYSTAL STRUCTURES OF Hg₂Mo₅O₁₆, HgVO₃, Hg₂VO₄, AND Hg₉As₄O₁₆. Manfred H. Möller, Annemarie L. Wessels, Wolfgang Jeitschko, Anorganisch-Chemisches Institut, Universität Münster, Wilhelm-Klemm-Str. 8, D-48149 Münster, Germany

The title compounds were prepared by reactions of binary and ternary oxides in evacuated silica tubes at temperatures between 400 and 550deg.C. Their crystal structures were determined and refined from single-crystal X-ray diffractometer data. Hg₂Mo₅O₁₆: P2/c, a = 913.9(1) pm, b = 551.3(1) pm, c = 1429.1(2) pm, [[beta]] = 110.65(1)deg., Z = 2, R = 0.043 (1129 structure factors, 66 variable parameters). HgVO₃: P1, a = 359.2(1) pm, b = 475.2(1) pm, c = 858.8(1) pm, [[alpha]] = 88.32(1)deg., [[beta]] = 79.60(1)deg., [[gamma]] = 89.30(1)deg., Z = 2, R = 0.034 (1763 F, 32 v). Hg₂VO₄: P2₁/n, a = 367.3(1) pm, b = 1650.3(1) pm, c = 1425.5(1) pm, [[beta]] = 89.99(1)deg., Z = 8, R = 0.038 (1668 F, 91 v). Hg₉As₄O₁₆: R3c, a= 1665.3(1) pm, c = 1083.79(7) pm, Z=6,R=0.037 (1661 F,62v).

Hg₂MO₅O₁₆ and HgVO₃ are Hg(I) compounds with Hg₂ pairs, Hg₂VO₄ is a mixed valent Hg(I, II) compound with Hg₂ pairs and isolated Hg atoms. In Hg₉As₄O₁₆ the mercury atoms form almost equilateral Hg₃ groups with the oxidation number +4. The molybdenum atoms have distortded octahedral coordination. These MoO₆ octahedra share corners and edges, thus forming two-dimensionally infinite sheets. The vanadium atoms are irregularly surrounded by five oxygen atoms. These coordination polyhedra share edges, thus forming infinite (VO₃^1-)n chains, which are aligned parallel to each other. The tetrahedral AsO₄ groups are linked only via Hg₃ triangles. Thus, the central atoms of the anions are in their highest oxidation state and the compounds may be represented by the formulas (Hg₂²⁺)_n(MO₅O₁₆^2-)_n, (Hg₂²⁺)_n(VO₃^1-)_2n, (Hg₂²⁺ * 2HgO)_n(VO₃^1-)_2n, and (Hg₃⁴⁺)₃(AsO₄^3-)₄.