Redetermination of the crystal structure of 3,5-di­methyl­pyrazolium β-octa­molybdate tetra­hydrate

The title compound, (C(5)H(9)N(2))(4)[Mo(8)O(26)]·4H(2)O, was reported previously from a room-temperature data collection from which only the metal atoms could be refined anisotropically [FitzRoy et al. (1989 ▸). Inorg. Chim. Acta, 157, 187–194]. The current redetermination at 180 (2) K models all the non-H atoms with anisotropic displacement parameters and fully describes the supra­molecular N—H⋯O and O—H⋯O hydrogen-bonded network connecting the 3,5-di­methyl­pyrazolium cations, the water mol­ecules of crystallization and the β-octa­molybdate anion. All H atoms involved in the three-dimensional hydrogen-bonding network could be located from difference Fourier maps, with the exception of those of one disordered water mol­ecule, firstly seen in this structural report [refined over two distinct locations with site-occupancy factors of 0.65 (2) and 0.35 (2)]. The complete β-octa­molybdate anion is generated by a crystallographic inversion centre.