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)₆ (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 P2₁/c) has been shown to feature a hexaquo complex of magnesium, the Mg(H₂O)²₆ 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.