4-(6-Fluoro-1,2-benzisoxazol-3-yl)-1-[2-(2-methyl-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-3-yl)ethyl]piperidinium nitrate

In the risperidone cation of the title compound, C23H28FN4O2 +·NO3 −, the piperidine ring adopts a chair conformation and the tetrahydropyridine ring is disordered over two orientations in a 0.620 (11):0.380 (11) ratio. N—H⋯O, C—H⋯O and C—H⋯F hydrogen bonds are present in the crystal structure.

In the risperidone cation of the title compound, C 23 H 28 FN 4 O 2 + ÁNO 3 À , the piperidine ring adopts a chair conformation and the tetrahydropyridine ring is disordered over two orientations in a 0.620 (11):0.380 (11) ratio. N-HÁ Á ÁO, C-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds are present in the crystal structure.
, one amino group and one carbonyl group in the risperidone molecule are involved in the hydrogen-bond network (Table 1, Fig. 2).

Experimental
All of the reagents and solvents were purchased from either Aldrich and used without further purification. The compound was recrystallized from a solution in a mixture of methanol and water, with the pH adjusted to 5-6 using 0.1 mol/l HNO 3 , giving colourless crystals of (I) suitable for X-ray diffraction.

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.
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.