Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.042 Å; Hatom completeness 78%; disorder in main residue; R factor = 0.053; wR factor = 0.155; data-to-parameter ratio = 12.2. 2+ cation is in a distorted octahedral environment, coordinated by six N atoms from three chelating 3-(2-pyridyl)-1H-pyrazole ligands. In the one-electron reduced heteropolyanion, two O atoms of the central PO 4 group (1 symmetry) are equally disordered about an inversion centre. N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds contribute to the crystal packing. Compared with the isotypic structures, the main difference is related with the M-N bond lengths, whereas all other bond lengths, angles and the hydrogenbonding motifs are very similar. Related literature ExperimentalCrystal data [Ni(C 8

The hydro­thermally prepared title compound, [Cd(C8H7N3)3]2[PMo12O40]·6H2O, is isotypic with its MnII analogue [Hao et al. (2010 ▶). Acta Cryst. E66, m231–m232]. The CdII cation is in a distorted octa­hedral environment, coordinated by six N atoms from three chelating 3-(2-pyrid­yl)-1H-pyrazole ligands. In the reduced heteropolyanion, two O atoms of the central PO4 group ( symmetry) are equally disordered about an inversion centre. N—H⋯O and O—H⋯O hydrogen bonds contribute to the crystal packing. Compared with the MnII analogue, the Cd—N bond lengths are longer at 2.316 (7)–2.334 (6) Å, versus 2.224 (6)–2.283 (5) Å for Mn—N, whereas all other bond lengths and angles and the hydrogen-bonding motifs are very similar in the two structures.

The asymmetric unit of the title compound, (C8H9N2)4[Mo8O26], consists of two 2-methyl­benzimidazolium cations and one-half of a β-Mo8O26 4− anion, which is completed by crystallographic inversion symmetry. An extensive net of N—H⋯O hydrogen bonds between the cations and anions contribute to the crystal packing.

In the title chromenone derivative, C10H8O2, the two fused six-membered rings are coplanar, with a mean deviation of 0.0261 (1) Å from the plane through the non-H atoms of the rings. The carbonyl and methyl substituents of the pyran ring also lie close to that plane, with the O and C atoms deviating by 0.0557 (1) and 0.1405 (1) Å, respectively. In the crystal, weak C—H⋯O contacts form chains along the a axis.

Crystals of the title compound, [Fe(C8H7N3)3]2[PMo12O40]·6H2O, prepared under hydro­thermal conditions, are isotypic with the Mn2+ and Cd2+ analogues. The Fe2+ cation is in a distorted octa­hedral coordination by six N atoms from three chelating 3-(2-pyrid­yl)-1H-pyrazole ligands. The heteropoly­anion [PMo12O40]4− is a one-electron reduced species in which two O atoms of the central PO4 group ( symmetry) are equally disordered about an inversion centre. N—H⋯O and O—H⋯O hydrogen bonds make a contribution to the crystal packing. The Fe—N bond lengths [2.085 (19)—2.15 (2) Å] are somewhat shorter than the Mn—N and Cd—N bond lengths [2.224 (6)–2.283 (5) and 2.316 (7)–2.334 (6) Å, respectively]. All other bond lengths and angles and the hydrogen-bonding motifs are very similar in the isotypic structures.