PROPERTIES AND CRYSTAL STRUCTURE OF LITHIUM DIMETHYLAMINOMETHANEDIPHOSPHONATE(1-) DIHYDRATE

Lithium dimethylaminomethanediphosphonate(1-) dihydrate (H3C)2HN+CH(PO3H)–2Li+·2H2O crystallizes from the aqueous solution at room temperature in the orthorhombic system (space group Pca21, a = 9,861(2) Å, b = 7,029(1) Å, c = 14,946(3) Å, z = 4). The crystal structure is determined by single-crystal X-ray diffraction analysis (R1 = 0,0737). The structure is constructed of zwitteranions (H3C)2HN+CH(PO3H)–2, cations Li+ and water molecules which are united together by interionic and hydrogen bonds. The zwitteranion is disordered: in the crystal there are two anions with occupancies of 0.5, which are linked together by pseudoplane, with common atom of phosphorus. The lithium cation occupying two positions with occupancies of ~ 0.5 is also disordered. The derivatography method has been used to study dehydration (tinit. 110–115 °С, tmin DTA 175 °С) and thermal stability (tinit. 240 °C) of the substance in the inert atmosphere. The list of wave numbers of absorption bands maxima in the IR spectrum is given. Solubility of the salt in water, in aqueous solutions of inorganic substances and in some particular organic solvents is evaluated.