N-Phenyl-N′-pyridylureas: stereochemical basis for anticonvulsant activity

Abstract

4-[N-(2-Chloro-6-methyl­phen­yl)ureido]pyridinium chloride, C13H13ClN3O+·Cl− (CI-953 hydro­chloride), crystallizes with Z′ = 2 in P\overline{1}. In both mol­ecules, the methyl groups and Cl atoms on the benzene rings are disordered. The benzene rings of mol­ecules A and B adopt two conformations, differing by a rotation of 180° about the C—N bond to the ureido group, in an approximate 1:1 ratio. This disorder is further enhanced by the rotation of the methyl groups in both adopted positions. The pyridine and benzene rings inter­sect at angles of 102.1 (1) and 111.3 (1)° for A and B, respectively. Hydrogen bonding is mediated by Cl− anions, resulting in indirect connectivity between the mol­ecules. Superposition of the mol­ecular structure, after 180° rotation about an amide bond, with that of phenytoin shows that the chemically different mol­ecules possess stereochemical features in common, which may explain their common activities.