title: Bis(hydrazin-1-ium) bis-(μ(2)-pyridazine-3,6-dicarboxyl-ato)bis-(aqua-lithiate) octa-aqua-bis-(μ(3)-pyridazine-3,6-dicarboxyl-ato)tetra-lithium.
abstract: The unit cell of the title compound, (N(2)H(5))(2)[Li(2)(C(6)H(2)N(2)O(4))(2)(H(2)O)(2)]·[Li(4)(C(6)H(2)N(2)O(4))(2)(H(2)O)(8)], comprises two centrosymmetric complexes, one double negatively charged and one neutral, and two mono-protonated hydrazine cations. The anionic complex molecule is a dimer, built of a pair of symmetry-related pyridazine-3,6-dicarboxyl-ate ligands and a pair of Li(I) ions, each coordinated by two N,O-chelating sites donated by a ligand mol-ecule and an aqua O atom at the apical position. The penta-coordination around the Li(I) ions is partway between a trigonal-bipyramidal and a square-pyramidal arrangement. The two carb-oxy-lic acid groups of the ligand are deprotonated and one carboxyl-ate O atom of each group is not involved in the coordination, and this applies to both the anionic and the neutral complex. The neutral complex molecule is also composed of a pair of Li(I) ions and a pair of ligand mol-ecules related by a centre of symmetry. They form a dimeric core in which the penta-coordination of the Li(I) ions includes two N,O-bonding groups donated by two ligands and an aqua O atom. The penta-coordination is described as partway between a trigonal-bipyramidal and a square-pyramidal arrangement. The coordinated carboxyl-ate group is bidentate-bridging, forming with an Li(H(2)O)(3) unit a neutral tetra-meric mol-ecule. The coordination of the tetra-coordinated Li(I) ion shows a slightly distorted tetra-hedral geometry. An extended system of O-H⋯O and N-H⋯O hydrogen bonds contributes to the stability of the crystal structure.
authors.affiliation: Institute of Nuclear Chemistry and Technology, ul. Dorodna 16, 03-195 Warszawa,  Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Starosta
authors.forename: Janusz
authors.initials: J
authors.lastname: Leciejewicz