Nonapiperidinium monohydrogen decavanadate tetranitrate

The title compound, (C5H12N)9[HV10O28](NO3)4, contains a monoprotonated decavanadate polyanion which lies on an inversion center. All the piperidinium cations adopt chair conformations. In the crystal structure, intermolecular N—H⋯O hydrogen bonds form chains along [001]. As well as half of a polyanion, the asymmetric unit contains one full and two half-occupancy nitrate ions and four full occupancy and one half-occupancy piperidinium cations; the half-occupancy piperidinium cation is disordered over two general sites with occupancies of 0.32 and 0.18, and is, in turn, disordered over an inversion center.

The title compound, (C 5 H 12 N) 9 [HV 10 O 28 ](NO 3 ) 4 , contains a monoprotonated decavanadate polyanion which lies on an inversion center. All the piperidinium cations adopt chair conformations. In the crystal structure, intermolecular N-HÁ Á ÁO hydrogen bonds form chains along [001]. As well as half of a polyanion, the asymmetric unit contains one full and two half-occupancy nitrate ions and four full occupancy and one half-occupancy piperidinium cations; the half-occupancy piperidinium cation is disordered over two general sites with occupancies of 0.32 and 0.18, and is, in turn, disordered over an inversion center.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH2828).
The asymmetric unit of (I) contains one half of a monoprotonated decavanadate polyanion [HV 10 O 28 ] 5-, 4.5 piperidinum cations (C 5 H 12 N + ), and 2 NO 3 anions. The formula unit is generated by a crystallographic inversion centre. The [HV 10 O 28 ] 5polyanion is composed of ten distorted VO 6 edge-sharing octahedra and is best described as cubic close-packing of oxygen ions, with the octahedral holes filled by vanadium ions. Each VO 6 octahedron is considerably distorted, with bond angles at the V atoms ranging from 1.602 (2) Silva et al., 2003;Maciejewska et al., 2003;Arrieta, 1992).
Similarly, we identified one disordered nitrate group, with a similar occupancy ratio for components N2O 3 A and N2O 3 B.
The central N atom of N1O 3 , N2O 3 A and of N2O 3 B nitrate groups is close to coplanarity with the three attached O atoms. The most important feature of this crystal is the presence of N-H···O, hydrogen bonds with D···A distances ranging from 2.693 (3) to 3.355 (13) Å. These interactions connect the various fragments into a supramolecular structure. In fact, it is noted supplementary materials sup-2 that piperidinium C 5 H 12 N + cations are located around the [HV 10 O 28 ] (Fig. 2). Each [HV 10 O 28 ] 5cluster is surrounded by ten C 5 H 12 N + cations. The N atoms of the organic cations are directing towards the doubly bridging O atoms of the cluster anion there by forming strong H-bonding. The NO 3 anions contribute to the cohesion of the structure by hydrogen bonds (Fig 2). In fact, as can be seen from the packing diagram (Fig. 2), there are intermolecular hydrogen bonds between the nitrato O atoms and the N-H group of the piperidinium C 5 H 12 N + cations.

Refinement
The positions of the H atoms attached to the piperidinium cations were placed at geometrically idealized positions (C-H = 0.97 Å, N-H =0.90 Å) and constrained to ride on their parent atoms with U iso (H)= 1.2U eq (carrier atom). The hydrogen atom attached to the [V 10 O 28 ] cluster could not be located but is included in the molecular formula. The disordered model was refined by using the tools available in the SHELXL97 (Sheldrick, 2008) software. Fig. 1. View of the decavanadate unit of the title compound. Thermal ellipsoids are drawn at 35% probability. The purple spheres are vanadium atoms and the red spheres are oxygen atoms.

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 > σ(F 2 ) is used only for calculating Rfactors(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.