metal-organic compounds
The crystal structures of two new salts of phosphoenolpyruvic acid (H3PEP), sodium hydrogen bis[2-(phosphonooxy)propenoate, Na+.C6H9O12P2−.2H2O, (I), and potassium hydrogen bis[2-(phosphonooxy)propenoate, K+.(C3H4O6P)−.(C3H5O6P), (II), have been determined. In the crystal of (I) the phosphate groups of two PEP residues related by a center of symmetry are joined by a very short disordered hydrogen bond with an OO distance of 2.456 (2) Å. As a result, the bis(phosphoenolpyruvate) monoanion can be distinguished. Crystals of (I) are almost isomorphous with crystals of zinc(II), manganese(II), magnesium and calcium bis(phosphoenolpyruvate) dihydrate and zinc(II) bis(phosphoglycolate) dihydrate. The crystal of (II) was found to be the 1:1 salt co-crystallized with the unionized molecular acid in the crystal chemical unit K+.H2PEP−.H3PEP. The P—O(ester) bond in acid molecule [1.578 (2) Å] is shorter than in the monoanion [1.618 (2) Å]. In the sodium salt this bond length is 1.612 (2) Å. In both crystals there are networks of strong hydrogen bonds.