| | 1 | Author
| R. Nagel3, M. Botovab, G. Pracht3, E. Suchanek3, M. Manevab, H. D. Lutz3 ', Herrn | Requires cookie* | | | Title
| Kristallstruktur, Infrarot-und Ramanspektren sowie thermische Zersetzung von Magnesiumtetrahydrogendimesoperiodat, MgH4I2O10 * 6H20 Crystal Structure, Infrared and Raman Spectra and Thermal Decomposition of Magnesium Tetrahydrogen Dimesoperiodate, MgH4I2O ,0 * 6H20  | | | | Abstract
| Crystal structure, DRIFT, infrared and Raman spectra, and the results of thermal analyses of the hitherto wrongly as Mg(H4I 0 6)2 • 4H20 and M g(I04) • 8H20 described dimesoperiodate MgH4I2O l0 • 6H20 and of the isostructural zinc compound are presented. The compounds crystallize in the monoclinic space group P2, (Z = 2) with a = 1071.0(2), b = 547.0(1), c = 1194.9(2) pm, and ß = 112.58(3)° and a = 1073.3(3), b = 545.3(2), c = 1188.3(5) pm, and ß = 112.52(3)°, respectively. The structure, which was refined from X-ray single crystal data of the magnesium compound (R 1 = 2.72%, 3824 independet reflections}, is built up from isolated distorted M(H20) 62+ octahedra and dimesoperiodate ions H4I2O 10 -connected by a network of hydrogen bonds formed by the H4I2O 10"~ ions and six crystallographically different hydrate H20 molecules. The strength of the hydrogen bonds ranges from unusually weak bonds corresponding to uncoupled (isotopically dilute samples) OD stretching modes of > 2600 cm-1 and ver^ strong ones (uOD: < 2200 cm-1). The IO stretching modes of the trans-configurated H4I2O l0~-ions are assigned to terminal 1-0 groups (816 cm-1), I-OH groups (746 and 762 cm' 1) and bridging 1-0 groups (618 and 647 cm-1). On heating, MgH4I2O |0 • 6H20 undergoes dehydration in the range of 373 -485 K (Differential Scanning Calorimetry) to two different polymorphs of magnesium metaperiodate (H4I2O |02-—» ■ 2 I0 4-+ 2H20). Anhydrous M g(I04)2 is instable. Above 423 K (high-temperature Raman data), it decomposes to magnesium iodates. | | | |
Reference
| Z. Naturforsch. 54b, 999—1008 (1999); eingegangen am 16. April 1999 | | | |
Published
| 1999 | | | |
Keywords
| Magnesium Periodate Hydrate, Zinc Periodate Hydrate, Dimesoperiodate Ions, Crystal Structure, Raman Data | | | |
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