Crystal and Molecular Structure of Perphenazine {2-Chloro-10-(3-[4-(2-hydroxyethyl)-piperazin-1-yl) propyl phenothiazine}: Conformational Variabilities of the Phenothiazine Ring

Abstract

Crystals of Perphenazine (P), obtained from water/propanol, are triclinic, space group P1, with a = 8.149 (2), b = 11.879 (2), c = 12.093 (2) A, α = 60.49(1), β = 89.54(2), γ = 89.98(2)°, V = 1018.9 A3, Z = 2, D obs = 1.32 g/cm3, D calc = 1.317 g/cm3. The crystal structure was solved with CAD-4 data (4287 reflections, 2267 ≥ 3σ) using the SHELX-86 programs and refined to a final R value of 0.059. There are two independent molecules in the asymmetric unit, each with slightly different conformations. The dihedral angle between the planes of the butterfly tricyclic ring system is 142° and 138° in the two molecules respectively whereas it is 141° in the published monoclinic form of Perphenazine. The C–S–C angle in the tricyclic groups are 97° and 100° and the C–S distances are 1.707 and 1.738 A. The piperazine has the chair conformation. An analysis of the conformation of the phenothiazine ring system in the different structures solved to date shows a conformational variability in the dihedral angle between the tricyclic ring systems (134–155°). Crystals of Perphenazine, obtained from water/propanol, are triclinic and their structure was determined using single crystal diffractometric data. There are two independent molecules in the asymmetric unit, each with slightly different conformations. An analysis of the conformation of the phenothiazine ring system in the different structures solved to date shows a conformational variability in the dihedral angle between the tricyclic ring systems (134–155˚).