catena-Poly[[aqua-lithium(I)]-μ-3-carb-oxy-5,6-di-methyl-pyrazine-2-carboxyl-ato-κ(4) O (2),N (1):O (3),N (4)]

The asymmetric unit of the title compound, [Li(C8H6N2O4)(H2O)] n , comprises three Li cations, two of which are located on a twofold rotation axis, two carboxylate anions and three water mol-ecules, of which two are situated on the twofold rotation axis being aqua ligands. Both carboxylate anions are in μ2-bridging mode. All Li ions show a trigonal-bipyramidal coordination mode; the two located in special positions are bridged through N,O-bonding sites generating a polymeric ribbon along the c-axis direction. The Li cation in a general position creates an independent polymeric ribbon through N,O-bonding sites of the two symmetry-related ligands; the trigonal-bipyramidal coordination is completed by an aqua ligand. In both carboxylate anions, a carboxyl-ate and a carb-oxy-lic acid group form an intra-molecular hydrogen bond. The polymeric ribbons running along [001] are inter-connected by hydrogen bonds in which the water mol-ecules act as donors and carboxyl-ate O atoms act as acceptors, giving rise to a three-dimensional architecture.