Crystal and molecular structure of 3-methyl-4-(2,4,6-triphenylpyridinium-1-yl)-phenolate salts with o-arsanilic and perchloric acids

The crystal structure for two salts of 3-methyl-4-(2,4,6-triphenylpyridinium-1-yl)-phenolate (1) with o-arsanilic (2-aminobenzene-arsonic) and perchloric acids were determined by X-ray diffraction. 1 was synthesized in order to break the symmetry of 4-(2,4,6-triphenylpyridinium-1-yl)-phenolate (2) and to overcome a tendency of the molecule for centrosymmetrical arrangement in a crystalline state. The structure of 1·HClO4 (space group Pbca) is governed by an antiparallel arrangement of pyridinium cations, connected to perchlorate anions through hydrogen bonds of O–H⋯O type. The crystals of 1·H2NC6H4AsO3H2·H2O belong to tetragonal space group I4¯. Due to strong O–H⋯O− and moderate N–H⋯O− interactions, hydrogen o-arsaniliate counterions form aggregates to which the cations of 1 are connected via O–H⋯OAs hydrogen bonds. The anionic aggregates are linked together by the crystallization water molecules through the system of hydrogen bonds.The comparison of the 1-(4-hydroxy-2-methylphenyl)-2,4,6-triphenylpyridinium hydrogen o-arsanilate and perchlorate structures reveals the importance of choosing the appropriate acids in order to obtain desired structure properties.