N-(4-{4-[2-(Trifluoromethoxy)phenyl]piperazin-1-yl}butyl)thiophene-2-carboxamide dihydrate

In the title compound, C20H24F3N3O2S·2H2O, a dopamine D3 ligand, the piperazine ring adopts a chair conformation while the piperazine and benzene rings form a dihedral angle of 47.71 (6)°. In the crystal, molecules are linked by intermolecular N—H⋯O and O—H⋯O hydrogen bonds. In the molecular structure, the F atoms of the trifluoromethyl group are disordered over two sites with occupancies of 0.69 (11) and 0.31 (11).

In the title compound, C 20 H 24 F 3 N 3 O 2 SÁ2H 2 O, a dopamine D3 ligand, the piperazine ring adopts a chair conformation while the piperazine and benzene rings form a dihedral angle of 47.71 (6) . In the crystal, molecules are linked by intermolecular N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds. In the molecular structure, the F atoms of the trifluoromethyl group are disordered over two sites with occupancies of 0.69 (11) and 0.31 (11).
We are grateful to the National Natural Science Foundation of China (project No. 30701052) for financial support.
activity relationships for dopamine D3 receptor are helpfull to rationalize the discovery of super-potent and highly selective dopamine D3 receptor antagonists and partial agonists (Bettinetti et al., 2002;Leopoldo et al., 2002;Dutta et al., 2004).

Refinement
All H atoms were placed in calculated positions, with O-H = 0.85 Å, N-H = 0.86 Å, and C-H = 0.93 or 0.97 Å, and included in the final cycles of refinement using a riding model, with U iso (H) = 1.2U eq (parent atom). The fluorine atoms of trifluoromethyl group is disordered over two sites with occupancies of 0.69 (11) and 0.31 (11). Due to the lack of any strong anomalous dispersor making absolute determination feasible, Friedel pairs were merged, thus leading to a rather poor data to parameters ratio.  Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme. The minor part of the disordered moieties was omitted for clarity.

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.