Crystal structure and Hirshfeld surface analysis of tetra-aqua-bis-(isonicotinamide-κ )nickel(II) fumarate.

The reaction of NiCl with fumaric acid and isonicotinamide in a basic solution produces the title complex, Ni(CHNO)(HO). The nickel(II) ion of the complex cation and the fumarate anion are each located on an inversion centre. The Ni ion is coordinated octa-hedrally by four water O atoms and two N atoms of isonicotinamide mol-ecules. The fumarate anion is linked to neighbouring complex cations O-H⋯O hydrogen bonds. In the crystal, the complex cations are further linked by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular architecture. Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyse the inter-molecular inter-actions present in the crystal and indicate that the most important contributions for the crystal packing are from H⋯O/O⋯H (41.8%), H⋯H (35.3%) and H⋯C/C⋯H (10.2%) inter-actions.