Cinnarizinium fumarate

In the title salt {systematic name: 4-diphenylmethyl-1-[(E)-3-phenylprop-2-en-1-yl]piperazin-1-ium (2Z)-3-carboxyprop-2-enoate}, C26H29N2 +·C4H3O4 −, the piperazine ring in the cation adopts a distorted chair conformation and contains a positively charged N atom with quaternary character. The dihedral angle between the mean planes of the phenyl rings of the diphenylmethyl group is 74.2 (7)° and those between these rings and the phenyl ring of the 3-phenylprop-2-en-1-yl group are 12.7 (9) and 80.6 (8)°. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds form chains along [001]. Weak C—H⋯O interactions connect parallel chains along [010], forming layers perpendicular to the a-axis direction.


Experimental
Cinnarizine (3.68 g, 0.01 mol) and fumaric acid (1.16 g, 0.01 mol) were dissolved in hot dimethyl sulphoxide solution and stirred over a heating magnetic stirrer for a few minutes. The resulting solution was allowed to cool slowly at room temperature. X-ray quality crystals of the title compound appeared after a few days. (m.p.: 468-471 K).

Refinement
H1N and H1O1 were located by Fourier maps and refined isotropically. All of the remaining H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.93Å (CH) or 0.97Å (CH 2 ).
Isotropic displacement parameters for these atoms were set to 1.19-1.21 (CH, CH 2 ) times U eq of the parent atom.

Figure 3
Packing diagram of the title compound viewed along the c axis. Dashed lines indicate weak C-H···O intermolecular interactions (Table 1) which are also observed connecting parallel chains along [010] to form layers perpendicular to the a-axis direction of the structure.

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 > 2sigma(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.