title: 4-Chloro-anilinium 2-carb-oxy-4,5-dichloro-benzoate.
abstract: The structure of the 1:1 proton-transfer compound of 4-chloro-aniline with 4,5-dichloro-phthalic acid (DCPA), viz. C(6)H(7)ClN(+)·C(8)H(3)Cl(2)O(4) (-), has been determined at 130 K. The non-planar hydrogen phthalate anions and the 4-chloro-anilinium cations form two-dimensional O-H⋯O and N-H⋯O hydrogen-bonded substructures which have no peripheral extension. Between the sheets there are weak π-π associations between alternating cation-anion aromatic ring systems [shortest centroid-centroid separation = 3.735 (4) Å].
authors.forename: Graham
authors.initials: G
authors.lastname: Smith
authors.forename: Urs D
authors.initials: UD
authors.lastname: Wermuth
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: White