Supramolecular Architecture in the 1:1 Co-Crystallization of 6,7-Dimethoxy-2-methyl-4-phenylisoquinolinium Cation with Perchlorate Anion

X-ray crystallographic analysis of the title organic ion-pair complex, C18H18NO2+ center dot ClO4-, reveals that 6,7-dimethoxy-2-methyl-4-phenylisoquinolinium cation is co-crystallized with perchlorate counter-anions in 1: 1 ratio. The complex crystallizes in space group P 2(1)/n, with a = 8.0226(7) angstrom, b = 12.2552(7) angstrom, c = 17.9734(16) angstrom, beta = 93.908(7) degrees, Z = 4, D-x = 1.431 g/cm(3). Aromaticity of isoquinolinium fragment is considerably deformed by the existence of C-H center dot center dot center dot O type weak H-bonds, leading to chains of topology C-3(3)(12)[R-1(2)(4)] running along b-axis of the unit cell and pseudo-cyclic centrosymmetric R-4(4)(24)[2R(1)(2)(4)] synthons. The weak H-bonds serve to stabilize both the extended structure and molecular geometry of the title complex, in particular the disordered perchlorate anion whose components adopt a distorted tetrahedron.