Hemipiperazinediium bis(pyridine-2,6-dicarboxylato-κ3O,N,O′)gallate(III) pyridine-2,6-dicarboxylic acid dihydrate

The asymmetric unit of the title compound, (C4H12N2)(0.5)-[ Ga(pydc)(2)]center dot pydcH(2)center dot 2H(2)O, where pydcH(2) is pyridine-2,6-dicarboxylic acid, C7H5NO4, contains one half of a centrosymmetric piperazinediium dication, one anion, one uncoordinated pydcH(2) molecule and two uncoordinated water molecules, one of which is disordered over two sites in a 1: 1 ratio. In the anion, the Ga-III ion is coordinated by four O atoms [Ga-O = 1.9706 (16)-2.0494 (15) angstrom] and two N atoms [Ga-N = 1.9660 (18) and 1.9709 (17) angstrom] from two pydc ligands in a distorted octahedral geometry. The crystal structure exhibits intermolecular O-H center dot center dot center dot O, N-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonds and pi-pi interactions [centroid centroid distances of 3.5359 (13) and 3.6550 (14) angstrom].