STRUCTURE AND VIBRATIONAL-SPECTRA OF THE TETRA(BETAINE) SELENATE CRYSTAL

The crystal structure of tetra(betaine) selenate has been determined b y X-ray diffraction as orthorhombic, space group Fddd, with a = 13.243 (8), b = 19.077(9) and c = 21.96(2) Angstrom, Z = 8. The crystal compr ises selenate ions, SeO42-, and the betaine dimers: two betaine moieti es are joined by a very strong symmetric (C-2) hydrogen bond with the O ... O distance of 2.424(6) Angstrom. Powder FTIR and FT-Raman spectr a were measured and assignment of the observed bands to vibrations of the hydrogen bonds and internal vibrations of the betaine molecules an d selenate ions is proposed.