Topological study of diverse hydrogen-bonded patterns found in a system of a nickel(II) complex and the sulfate anion

A nickel(II) coordination complex, bis[2,6-bis(1H-benzimidazol-2-yl-κN³)pyridine-κN]nickel(II) sulfate, [Ni(C₁₉H₁₃N₅)₂]SO₄ or [Ni(H₂L)₂]SO₄, having four peripheral tetrahedrally oriented N-H donor units, combines with sulfate bridges to create hydrogen-bonded structures of varied dimensionality. The three crystal structures reported herein in the space groups P2₁2₁2₁, I-4 and Pccn are defined solely by strong charge-assisted N-H...O hydrogen bonds and contain disordered guests (water and dimethylformamide) that vary in size, shape and degree of hydrophilicity. Two of the compounds are channelled solids with three-dimensional structures, while the third is one-dimensional in nature. In spite of their differences, all three present a striking resemblance to the previously reported anhydrous relative [Guo et al. (2011). Chin. J. Inorg. Chem. 27, 1517-1520], which is considered as the reference framework from which all three title compounds are derived. The hydrogen-bonded frameworks are described and compared using crystallographic and topological approaches.