Bis{tris[3-(2-pyridyl)-1 H -pyrazole]iron(II)} tetradecamolybdo(V,VI)silicate

The asymmetric unit of the title compound, [Fe(C8H7N3)3]2[SiMo14O44], consists of a complex [Fe(C8H7N3)3]2+ cation and half of a derivative of an α-Keggin-type anion, [SiMo14O44]4−. In the mixed-valent MoV/VI anion, the α-Keggin type core is capped on two oppositely disposed tetragonal faces by additional (MoO2) units. The [SiMo14O44]4− anion shows disorder. Two O atoms of the central SiO4 group (overline{1} symmetry) are equally disordered about an inversion centre. Moreover, two of the outer bridging O atoms and the O atoms of the capping (MoO2) unit are likewise disordered. The Fe2+ cation is surrounded in a slightly distorted octahedral coordination by six N atoms from three 3-(2-pyridyl)-1H-pyrazole ligands. N—H...O hydrogen bonding between the cations and anions leads to a consolidation of the structure.