catena-Poly[[[[3-(2-pyridyl)-1H-pyrazole]nickel(II)]-μ-oxalato] sesquihydrate]

In the title compound, {[Ni(C2O4)(C8H7N3)]·1.5H2O}n, both unique NiII ions are chelated by an O,O′-bidentate oxalate ion and an N,N′-bidentate 3-(2-pyridyl)pyrazole molecule. A second, symmetry-generated, oxalate ion completes a distorted cis-NiN2O4 octahedral geometry for both metal centres. The bridging oxalate ions result in two distinct wave-like polymeric chains propagating in [100]. The packing is consolidated by N—H...O and O—H...O hydrogen bonds. The crystal studied was found to be an inversion twin