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

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.

Crystals of the title compound, [Fe(C 8

Experimental
Crystal data [Fe(C 8   (2-pyridyl)-1H-pyrazole and pyrazine, are used to effectively modify polyoxomolybdates under hydrothermal condictions . Here, we describe the synthesis and structural characterization of the title compound.
As shown in Figure 1, the asymmetric unit of the title compound consists of three subunits, viz. of a complex  (2000); Kurmoo et al. (1998);Niu et al. (1999). The employed organic ligand appears to adjust the pH value, and additionally supplies reducing electrons, which is a commonly observed feature of hydrothermal syntheses when organic amines are used to prepare various hybrid materials, zeolites or metal phosphates (Yang et al., 2003).
In the Keggin-type heteropolyanion, each Mo atom is surrounded by six O atoms and the P atom is located at the center  Table 2).
TGA curve shows a separation of lattice water molecules and the organic ligands above 352 and 655 K, respectively.
The overall thermal decomposition process can be described by the followed equation

Refinement
All hydrogen atoms bound to aromatic carbon atoms were refined in calculated positions using a riding model with a C-H distance of 0.93 Å and U iso = 1.2U eq (C). Hydrogen atoms attached to aromatic N atoms were refined with a N-H distance of 0.86 Å and U iso = 1.2U eq (N). The hydrogen atoms of the three uncoordinated water molecules could not be located unambiguously from difference Fourier maps, probably due to disorder of the water molecules. Thus the structure was refined without the H atoms of the water molecules (which includes the water O atoms O1W, O2W, O3W). In the PO 4 unit, the two oxygen atoms (O19 and O21) are equally disordered about the inversion centre. In the final difference Fourier map the highest peak is 2.82 Å from atom O2w and the deepest hole is 0.79 Å from atom Mo1. The highest peak is located in the voids of the crystal structure and may be associated with an additional water molecule. However, refinement of this position did not result in a reasonable model. Hence this position was also excluded from the final refinement.
Figures Fig. 1. The building blocks of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level; H atoms are given as spheres of arbitrary radius.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.