Tris(1,10-phenanthroline-κ²N,N′)nickel(II) hexa­oxido-μ-peroxido-disulfate­(VI) N,N-dimethyl­formamide disolvate monohydrate

The asymmetric unit of the title complex, [Ni(C₁₂H₈N₂)₃]S₂O₈·2C₃H₇NO·H₂O, consists of a complex [Ni(phen)₃]²⁺ cation and one isolated pds anion, with two DMF mol­ecules and one water mol­ecule as solvates (where phen is 1,10-phenanthroline, pds is the hexa­oxido-μ-peroxoido-di­sulf­ate dianion and DMF is dimethyl­formamide). The [Ni(phen)₃]²⁺ cation is regular, with an almost ideal Ni^II bond-valence sum of 2.07 v.u. The group, as well as the water solvent mol­ecule, are well behaved in terms of crystallographic order, but the remaining three mol­ecules in the structure display different kinds of disorder, viz. the two DMF mol­ecules mimic a twofold splitting and the pds anion has both S atoms clamped at well-determined positions but with a not-too-well-defined central part. These peculiar behaviours are a consequence of the hydrogen-bonding inter­actions: the outermost SO₃ parts of the pds anion are heavily connected to the complex cations via C—H...O hydrogen bonding, generating an [Ni(phen)₃]pds network and providing for the stability of the terminal pds sites. Also, the water solvent mol­ecule is strongly bound to the structure (being a donor of two strong bonds and an acceptor of one) and is accordingly perfectly ordered. The peroxide O atoms in the pds middle region, instead, appear as much less restrained into their sites, which may explain their tendency to disorder. The cation–anion network leaves large embedded holes, amounting to about 28% of the total crystal volume, which are occupied by the DMF mol­ecules. The latter are weakly inter­acting with the rest of the structure, which renders them much more labile and, accordingly, prone to disorder.