OROTATE COMPLEXES - SYNTHESIS AND CRYSTAL-STRUCTURE OF LITHIUM OROTATE(-I) MONOHYDRATE AND MAGNESIUM BIS[OROTATE(-I)] OCTAHYDRATE

Neutralization of orotic acid (OrH2) by lithium or magnesium hydroxide in aqueous medium yields the crystalline metal orotate hydrates Li(OrH).H2O (1) and Mg(OrH)2. (H2O)8 (2). By single-crystal X-ray diffraction studies it has been shown that 1 (space group P1) forms a layer structure, with lithium in a tetrahedral environment of oxygen atoms from three different orotate(-I) anions (one carboxylate and two uracil oxygen atoms) and the water molecule. 2(space group P2(1)/c) has been shown to feature a hexaquo complex of magnesium, the Mg(H2O)62 + cations being associated with two hydrated OrH-ions only through hydrogen bonds. The anions are also engaged in ''base-pairing'' hydrogen bonds between the planar uracil ring systems of different units. The results are relevant for applications of magnesium orotates in magnesium therapy.