Crystal structure of an antipsychotic agent, 2-(4-ethyl-1-piperazinyl)-4-(4-fluorophenyl)-5,6,7,8,9,10-hexahydrocycloocta[b]pyridine (blonanserin).

both dopamine D2 and serotonin 5-HT2 receptor antagonist properties.1 In the chemical structure, this compound is different from all of the currently known antipsychotics, such as haloperidol, chlorpromazine and risperidone.2 To understand the structure-activity relationships of antipsycotics, an X-ray analysis of the title compound was undertaken. A colorless platelet crystal was obtained from a chloroform solution at room temperature. The crystal and experimental data are given in Table 1. The structure was solved by direct methods and refined by full-matrix least-squares methods with anisotropic thermal parameters for non-hydrogen atoms. Hydrogen atoms were placed at their idealized positions and included in a structure factor calculation with fixed isotropic thermal parameters. The least-squares weights were as follows: ω = [σ2(Fo)2 + (0.0013P)2 + 0.7458P]–1, where P = (Fo2 + 2Fc2)/3. The final coordinates of the non-hydrogen atoms are listed in Table 2. The bond distances, selected bond and torsion angles are given in Table 3. An ORTEP III3 drawing of the 1289 ANALYTICAL SCIENCES NOVEMBER 2002, VOL. 18 2002 © The Japan Society for Analytical Chemistry