Crystal structure of bis­(di­methyl­ammonium) hexa­aqua­cobalt(II) bis­(sulfate) dihydrate

The title salt, (C(2)H(8)N)(2)[Co(H(2)O)(6))](SO(4))(2)·2H(2)O, is isotypic with (C(2)H(8)N)(2)[Ni(H(2)O)(6))](SO(4))(2)·2H(2)O. The Co—O bond lengths in the [Co(H(2)O)(6)](2+) complex cation show very similar distances as in the related Tutton salt (NH(4))(2)[Co(H(2)O)(6))](SO(4))(2) [average 2.093 (17) Å], but are significantly longer than in the isotypic Ni(II) compound (Δd ≃ 0.04 Å). The cobalt cation reaches an overall bond-valence sum of 1.97 valence units. The S—O distances are nearly equal, ranging from 1.454 (4) to 1.470 (3) Å [mean 1.465 (12) Å]; however, the O—S—O angles vary clearly from 108.1 (2) to 110.2 (2)° [average bond angle 109.5 (9)°]. The non-coordinating water mol­ecules and di­methyl­ammonium cations connect the sulfate tetrahedra and the [Co(H(2)O)(6)](2+) octa­hedron via O—H⋯O and N—H⋯O hydrogen bonds of weak up to medium strength into a three-dimensional framework whereby the complex metal cations and sulfate anions are arranged in sheets parallel to (001).