Zur Kenntnis von Calciumtetrahydrogen-hexaoxo- diperiodattetrahydrat Ca H4 I2 O10 * 4(H2 O): Kristallstruktur, Schwingungsspektren und thermische Analyse

By crystallisation from a strongly acidic aqueous solution calciumtetrahydrogen-hexaoxo-di-periodatetetrahydrate CaH 4 I 2 O 1 0 . 4 H 2 O has been obtained. In the structure of this compound (S. G. C2/c, Nr. 15), Z = 4, a =1986,6(4), b = 564,2(1), c = 1149,4(20) pm, β = 120,62(3)°) centrosymmetric H 4 I 2 O 1 0 2- anions in the form of edge-sharing octahedra form layers via hydrogen bonds originating from the acidic, trans-configurated OH groups of the anions. IR and Raman spectra are analysed with respect to the hydrogen bond system and the internal vibrations of the periodate anion. The dehydration of the compound takes place via Ca(IO 4 ) 2 . 5 H 2 O and Ca(IO 4 ) 2 .2H 2 O leading at 143 °C to the anhydrous metaperiodate Ca(IO 4 ) 2 which decomposes above 248 °C to Ca(IO 3 ) 2 .