Crystal structure and Hirshfeld surface analysis of tetra­aqua­bis­(isonicotinamide-κN (1))nickel(II) fumarate

The reaction of NiCl(2) with fumaric acid and isonicotinamide in a basic solution produces the title complex, [Ni(C(6)H(6)N(2)O)(2)(H(2)O)(4)](C(4)H(2)O(4)). The nickel(II) ion of the complex cation and the fumarate anion are each located on an inversion centre. The Ni(II) ion is coordinated octa­hedrally by four water O atoms and two N atoms of isonicotinamide mol­ecules. The fumarate anion is linked to neighbouring complex cations via O(water)—H⋯O(fumarate) 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 supra­molecular architecture. Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyse the inter­molecular inter­actions 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%) inter­actions.