Crystal structure and vibrational spectra of BaH4I2O10·2H2O

By crystallization from strongly acidic aqueous solutions barium-tetrahydrogen-decaoxodiperiodate-dihydrate, BaH4I2O10·2H2O has been obtained (S.G. C2/c, No. 15) with the lattice constants a = 12.728(3), b = 7.987(2), c = 9.459(2), and β = 94.07(3). IR and Raman spectra are given and analysed with respect to the internal vibrations of the H 4 I 2 O 10 2 - ion and the hydrogen bond system. According to high temperature Raman spectra and DTA and TG measurements, the compound decomposes via unknown salts with the anion IO 4 - above 230 °C to the corresponding iodate which above 575 °C starts to disproportionate to the periodate Ba5(IO6)2.