CRYSTAL STRUCTURE OF 4,4'-DICHLORO-2,2' IMINODIBENZOIC ACID. RamÛn PomÈs Hern.ndez^*, HÈctor Novoa de Armas¹, Julio Duque RodrÌguez, Ra[[dotaccent]]l Alfredo Toscano², National Center for Scientific Research. P. O. Box 6990, Havana, Cuba, ¹ Center of Pharmaceutical Chemistry. P. O. Box 16042, Havana, Cuba, ² Institute of Chemistry, UNAM, MÈxico, D. F.

In the title compound, C₁₄H₁₀Cl₂NO₄ , although the pharmacological activity has not been tested, the substituents bounds to diphenylamine skeleton causes this compound to be an analogue of Lobenzarit acid. Lobenzarit acid (4-chloro-2,2'-iminodibenzoic acid) is an intermediary compound in the synthesis of Lobenzarit disodium (CCA, Disodium 4-chloro-2,2'-iminodibenzoate) which is an anti-rheumatic drug.

Aromatic rings in the title compound are planar and the dihedral angle between the two planes is 44.8(3)[[infinity]], the out-of-plane r.m.s. deviation being 0.007~. An internal N--H...O bifurcated hydrogen bond with the imino N atom as donor and a carbonyl O atom as the acceptor is present [N(1)...H(1) 2.12(6)~, N(1)--H(1)...O(1) 129(6)[[infinity]] and H(1)...O(4) 2.16(6)~, N(1)--H(1)...O(4) 124(6)[[infinity]]]. The imino group is not involved in intermolecular interactions, a common feature of related compounds such as fenamates. Therefore, the carboxyl group is the only common site of specific interaction appearing to be as a site for intermolecular interactions. A dimerization occurs through hydrogen bonding of the carboxylic groups [H(3a)...O(3) 1.351(9)~ and H(4)...O(4a) 1.351(9)~, symmetry: 2-x, y, 0.5-z]. The H atoms of the carboxylic group C(14) O(3) O(4) were tied in special position constrains (for H(3a): x = 1.00, z = 0.25 and s.o.f. = 0.50; for H(4): x = 1.00, z = 0.25 and s.o.f. = 0.50, input constraints retained, at least in part, for xyz, s.o.f. and Uij in both cases. The bonds lengths are in good agreement with the average literature values. Crystals are orthorhombic, Pbcn, Z = 8, a = 8.653(2), b = 20.225(4), c = 14.724(3)~.