Crystal structure of bis-(di-methyl-ammonium) hexa-aqua-nickel(II) bis-(sulfate) dihydrate.

In the title salt, (C2H8N)2Ni(H2O)6)2·2H2O, the Ni(II) cation is located on a centre of inversion and exhibits a slightly distorted octa-hedral arrangement of water mol-ecules. The Ni-O bond lengths in the complex Ni(H2O)6 cation show a distribution as in the related Tutton salt (NH4)2Ni(H2O)62, but are longer in average [2.056 (13) versus 2.037 (12) Å]. The noncoordinating water mol-ecules and di-methyl-ammonium cations connect the sulfate and Ni(H2O)6 octa-hedra via O-H⋯O and N-H⋯O hydrogen bonds from weak up to medium strength into a three-dimensional framework whereby the complex metal cations and sulfate anions are arranged in sheets parallel (001).