IR- und Raman-Spektren der isotypen Iodathydrate M(IO3)2 · 4 H2O (M = Mg,Ni, Co); Kristallstruktur von Co(IO3)2 · 4 H2O |
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| Authors: | G Pracht R Nagel E Suchanek N Lange H D Lutz M Maneva |
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| Abstract: | Infrared and Raman Spectroscopy of the Isostructural Iodate Hydrates M(IO3)2 · 4 H2O (M = Mg, Ni, Co)-Crystal Structure of Cobalt Iodate Tetrahydrate The iodate tetrahydrates Mg(IO3)2 · 4 H2O, β-Ni(IO3)2 · 4 H2O, Co(IO3)2 · 4 H2O and their deuterated specimens were studied by X-ray, infrared and Raman spectroscopic methods. The title compounds are isostructural crystallising in the monoclinic space group P21/c (Z = 2). The crystal structure of Co(IO3)2 · 4 H2O (a = 836.8(5), b = 656.2(3), c = 850.2(5) pm and β = 100.12(5)°) has been refined by single-crystal X-ray methods (Robs = 3.08%, 693 unique reflections I0 > 2σ(I)). Isolated Co(IO3)2(H2O)4 octahedra form layers parallel (100). Within these layers, the two crystallographically different hydrate water molecules form nearly linear hydrogen bonds to adjacent IO3– ions (νOD of matrix isolated HDO of Co(IO3)2 · 4 H2O (isotopically diluted samples) 2443 (H3), 2430 (H2), and 2379 cm–1 (H1 and H4), –180 °C). Intramolecular O–H and intermolecular H…O distances were derived from the novel νOD vs. rOH and the traditional νOD vs. rH…O correlation curves, respectively. The internal modes of the iodate ions of the title compounds are discussed with respect to their coupling with the librations of the hydrate H2O molecules, the distortion of the IO3– ions, and the influence of the lattice potential. |
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| Keywords: | Magnesium iodate hydrate Nickel iodate hydrate Cobalt iodate hydrate Crystal structure IR Raman Hydrogen bonds |
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