Benzamidinium 2-methoxybenzoate

Abstract

The title molecular salt, C7H9N2+.C8H7O3−, was synthesized by reaction between benzamidine (benzenecarboximidamide) and 2-methoxybenzoic acid. In the cation, the amidinium group has two similar C—N bonds [1.3070 (17) and 1.3145 (16) Å] and is almost coplanar with the benzene ring, making a dihedral angle of 5.34 (12)°. In the anion, the methoxy substituent forces the carboxylate group to be twisted by 69.45 (6)° with respect to the plane of the aromatic fragment. In the crystal, the components are connected by two N+—H...O− (±)CAHB (charge-assisted hydrogen bonds), forming centrosymmetric ionic dimers with graph-set motif R22(8). These ionic dimers are then joined in ribbons running along the b-axis direction by another R42(8) motif involving the remaining N+—H...O− hydrogen bonds. Remarkably, at variance with the well known carboxylic dimer R22(8) motif, the carboxylate–amidinium pair is not planar, the dihedral angle between the planes defined by the CN2+ and CO2− atoms being 18.57 (12)°.