Crystallochemistry of mercury chalcogenides. IV. Crystalline structure of two polymorphous modifications of the mercury sulfochalcogenide Hg3S2Br1.5Cl0.5 |
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Authors: | N V Pervukhina S A Magarill D Yu Naumov S V Borisov V I Vasil’yev B G Nenashev |
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Institution: | (1) A. V. Nikolayev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences, Novosibirsk;(2) United Institute of Geology, Geophysics and Mineralogy, Siberian Division, Russian Academy of Sciences, Novosibirsk |
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Abstract: | Two modifications of a new mercury sulfohalide of Hg3S2Br2?x Clx (x = 0.5) composition have been grown from the gas phase and explored by X-ray structural analysis. The compounds were obtained at an attempt to synthesize an analogue of the rare mineral arzakite Hg3S2(Br, Cl)2 (Br > Cl). The refinement of the crystalline structures of monoclinic (I) and cubic (II) phases (I: a = 17.824(4) Å, b = 9.238(2) Å, c = 10.269(2) Å, β = 115.69(1)°, V = 1523.8(5) Å3, space group C2/m, Z = 8, R = 0.0513; II: a = 18.248(2) Å, V = 6076.4(12) Å3, space group Pm3¯n, Z = 32, R = 0.038) has shown that they are polymorphous modifications of the compound of Hg3S2Br1.5Cl0.5 formula. The monoclinic modification I is isostractural to the synthetic compound α-Hg3S2Br2. Modification II is isostructural to synthetic β-Hg3S2Cl2. In both structures, each atom S has in its surrounding three atoms of Hg forming umbrella-type groups SHg3 with spaces Hg—S 2.366–2.430 Å and angles HgSHg 95.66–97.60°. SHg3-fragments are bound by Hg-apices with the formation of isolated cubic groups Hg12S8]. Like that in other structures of mercury chalcohalides, the main role in structure-forming of the investigated compounds is played by atoms of halogens creating a cubic sublattice in which radicals Hg—S are arranged. |
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Keywords: | mercury chalcohalides of mercury mercury minerals crystalline structure X-ray structural analysis isomorphism polymorphism |
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