Crystal structure of octakis(N,N-dimethylformamide-κO)europium(III) tetracosa-μ2-oxido-dodecaoxido-μ12-phosphato-dodecamolybdate(VI)

The asymmetric unit of the title compound consists of one [Eu(C3H7NO)8]3+ complex cation and one α-Keggin-type [PMo12O40] polyanion. Cations and anions are linked through C—H⋯O hydrogen bonds.


Chemical context
Polyoxidometalates (POMs) are versatile metal-oxygen complexes which have attracted interest due to their topological properties and their potential applications in catalysis, photoluminescence, electrochromism and magnetism (Long et al., 2010;Pope & Mü ller, 2010;Coronado & Gó mez-García, 1998). Up to date, a variety of strategies have been developed and used to assemble POM-based hybrid materials by controlling reaction factors such as metal ions, organic ligands, POM species, pH, molar ratio of raw materials or reaction environments (Wang et al., 2013;Liu et al., 2013). Even with these approaches, the design and synthesis of new stable polyoxidomolybdate complexes are still challenging.

Figure 1
The molecular structures of the cation and anion in compound (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level. H atoms have been omitted for clarity.

Figure 2
The contents of the unit cell of complex (I). H atoms have been omitted for clarity.

Synthesis and crystallization
The starting material [(C 4 H 9

FT-IR spectroscopy
The FT-IR spectrum was recorded in the range 4000-400 cm À1 on a Nicolet 470 FT-IR spectrophotometer with pressed KBr pellets.
The FT-IR spectrum of (I) (

Figure 4
The crystal packing of (I) with the [PMo 12 O 40 ] 3À anions in polyhedral representation.

Octakis(N,N-dimethylformamide-κO)europium(III) tetracosa-µ 2 -oxido-dodecaoxido-µ 12 -phosphatododecamolybdate(VI)
Crystal data   (7) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.