Bis(carboxy-meth-yl)ammonium 4-toluene-sulfonate

The imino-diacetic acid component of the title salt, C(4)H(8)NO(4) (+)·C(7)H(7)SO(3) (-), is protonated at the N atom. The cation uses the ammonium group to form hydrogen bonds to the O atoms of two adjacent sulfonate groups. In addition, the carboxylic acid portions of the cation form hydrogen bonds to the sulfonate groups. The hydrogen-bonding inter-actions give rise to a layer structure.