Crystal structure of zwitterionic 4-(ammonio-methyl)-benzoate: a simple mol-ecule giving rise to a complex supra-molecular structure.

ABSTRACT

The asymmetric unit of the title compound, C8H9NO2·H2O consists of an isolated 4-(ammonio-meth-yl)benzoate zwitterion derived from 4-amino-methyl-benzoic acid through the migration of the acidic proton, together with a water molecule of crystallization that is disordered over three sites with occupancy ratios (0.500.350.15). In the crystal structure, N-H⋯O hydrogen bonds together with π-π stacking of the benzene rings [centroid-centroid distance = 3.8602 (18) Å] result in a strongly linked, compact three-dimensional structure.