Pyrimethaminium 2-{[4-(trifluoromethyl)phenyl]sulfanyl}benzoate dimethyl sulfoxide monosolvate

In the cation of the title solvated molecular salt, C12H14ClN4 +·C14H8F3O2S−·C2H6OS [systematic name of the cation: 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium], the dihedral angle between the planes of the pyrimidinium and 4-chlorophenyl rings is 77.2 (5)°. In the anion, the planes of the benzene rings are twisted with respect to each other by 71.5 (5)°. Disorder was modelled for the dimethyl sulfoxide solvent molecule over two set of sites in a 0.7487 (13):0.2513 (13) ratio. In the crystal, the cations are linked by inversion-generated pairs of N—H⋯N hydrogen bonds, with an R 2 2(8) graph-set motif. The cation donates two N—H⋯O hydrogen bonds to the anion, also generating an R 2 2(8) loop. These interactions, along with cation–solvent N—H⋯O hydrogen bonds, and cation–anion C—H⋯F, solvent–anion C—H⋯O and C—H⋯F interactions, result in a three-dimensional network.

medication used in combination with other drugs for treatment of protozoan disease like toxoplasmosis, bacterial infections and some types of cancer (Zuccotto et al., 1998;Kraut & Matthews, 1987). Pyrimethamine (PMN) exhibits a donor-acceptor-donor site, so that together with a complimentary molecule it can form three hydrogen bonds, yielding a robust supramolecular synthon (Desiraju, 1995). The crystal structure of 2-amino-4,6-dimethylpyrimidine-cinnamic acid In the cation, the dihedral angle between the mean plane of the pyrimidinium and the 4-chlorophenyl ring is 77.2 (5)°.
In the anion, the mean planes of the two phenyl rings are twisted with respect to each other by 71.5 (5)°. Disorder was modelled for the dimethyl sulfoxide solvent molecule over two sites in a 0.7487 (13):0.2513 (13) ratio. Within the asymmetric unit, cation-anion N-H···O hydrogen bonds (forming R 2 2 (8) graph-set ring motifs) along with cation-cation N-H···N hydrogen bonds are observed. In the crystal additional cation-cation N-H···N hydrogen bonds and cationsolvate N-H···O hydrogen bonds help to consolidate the packing (Fig. 2). Weak cation-anion C-H···F, and solvateanion C-H···O, C-H···F are also observed (Table 1).
After few days, irregular colourless chunks of the title compound were developed (m.p: 383-388 K).

Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.95Å (CH); 0.99Å (CH 2 ); 0.98Å (CH 3 ) or 0.88Å (NH, NH 2 ). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH 2 , NH, NH 2 ) or 1.5 (CH 3 ) times U eq of the parent atom. Idealised Me groups refined as rotating groups. Disorder was modelled for the S1S, O1S, C1S and C2S atoms of the dimethyl sulfoxide solvent molecule over two sites in a 0.7487 (13)

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.