Monoclinic form i of clopidogrel hydrogen sulfate from powder diffraction data

Abstract

The asymmetric unit of the title compound, C16H 17ClNO2S+·HSO4-, (I) [systematic name: (+)-(S)-5-[(2-Chlorophenyl)(methoxycarbonyl)methyl]-4,5,6, 7-tetrahydro-thieno[3,2-c]pyridin-5-ium hydrogen sulfate], contains two independent cations of clopidogrel and two independent hydrogensulfate anions. The two independent cations are of similar conformation; however, this differs from that observed in ortho-rhom-bic form (II) [Bousquet et al. (2003). US Patent No. 6 504 030]. The H - N - Cchiral - H fragment shows a trans conformation in both independent cations in (I) and a gauche conformation in (II). In (I), classical inter-molecular N - H⋯O and O - H⋯O hydrogen bonds link two independent cations and two independent anions into an isolated cluster, in which two cations inter-act with one anion only via N - H⋯O hydrogen bonds. Weak inter-molecular C - H⋯O hydrogen bonds further consolidate the crystal packing.