Single Crystal Growth and Crystal Structure of Anhydrous Mercury(I) Nitrate,Hg2(NO3)2 |
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Authors: | Matthias Weil |
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Abstract: | Polycrystalline anhydrous Hg2(NO3)2 was prepared by drying Hg2(NO3)2·2H2O over concentrated sulphuric acid. Evaporation of a concentrated and slightly acidified mercury(I) nitrate solution to which the same volumetric amount of pyridine was added, led to the growth of colourless rod‐like single crystals of Hg2(NO3)2. Besides the title compound, crystals of hydrous Hg2(NO3)2·2H2O and the basic (Hg2)2(OH)(NO3)3 were formed as by‐products after a crystallization period of about 2 to 4 days at room temperature. The crystal structure was determined from two single crystal diffractometer data sets collected at —100°C and at room temperature: space group P21, Z = 4, —100°C room temperature]: a = 6.2051(10) 6.2038(7)]Å, b = 8.3444(14) 8.3875(10)]Å, c = 11.7028(1) 11.7620(14)]Å, ß = 93.564(3) 93.415(2)]°, 3018 3202] structure factors, 182 182] parameters, RFμ2 > 2σ(Fμ2)] = 0.0266 0.0313]. The structure is built up of two crystallographically inequivalent Hg22+ dumbbells and four NO3— groups which form molecular O2N‐O‐Hg‐Hg‐O‐NO2] units with short Hg‐O bonds. Via long Hg‐O bonds to adjacent nitrate groups the crystal packing is achieved. The Hg‐Hg distances with an average of d(Hg‐Hg) = 2.5072Å are in the typical range for mercurous oxo compounds. The oxygen coordination around the mercury dumbbells is asymmetric with four and six oxygen atoms as ligands for the two mercury atoms of each dumbbell. The nitrate groups deviate slightly from the geometry of an equilateral triangle with an average distance of d(N‐O) = 1.255Å. |
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Keywords: | Mercury Mercury nitrate Crystal structure Crystal chemistry |
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