(Propane-1,3-diammonium) bis(4-hydroxypyridine-2,6-dicarboxylato-κ3O2,N,O6)zinc(II) 3.5-hydrate

The asymmetric unit of the title compound, (C3H12N2)[Zn(C7H3NO5)(2)]center dot 3.5H(2)O, contains two formula units. The compound consists of an anionic complex, a doubly protonated propane-1,3-diamine as a counter-ion and 3.5 uncoordinated water molecules. The coordination polyhedron around the Zn-II atom is distorted octahedral, defined by four O atoms and two N atoms from two Hchel (H(3)chel = 4-hydroxypyridine-2,6-dicarboxylic acid) ligands. In the crystal structure, O-H center dot center dot center dot O, N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds along with pi-pi stacking interactions [centroid-centroid distance = 3.473 (2) angstrom] are observed to reinforce the crystal cohesion.