3,5-DIMETHOXYBENZOIC ACID AND THE 2ND POLYMORPH OF THE 2 1-ADDUCT OF 3,5-DINITRO-BENZOIC ACID WITH ETHYLENEDIAMINE/

3,5-Dimethoxybenzoic acid, C9H10O4, is planar and forms hydrogen-bonde d cyclic dimers [O...O = 2.644 (2) Angstrom]. The second (monoclinic) polymorph of the 2:1 adduct of 3,5-dinitrobenzoic acid with ethylenedi amine, ethylenediammonium 3,5-dinitrobenzoate, C2H10N22+.2C(7)H(3)N(2) O(6)(-) [(DNBA)(2)(-)(en)(2+)], is structurally identical to the previ ously reported triclinic form. It forms a 12-membered hydrogen-bonded ring involving the carboxylate groups of the acids and the protonated amine groups of ethylenediamine. Hydrogen-bond distances (O...N) are 2 .678 (2) and 2.729 (2) Angstrom. A nitro group is also involved in a l onger intermolecular interaction with an amine group [O...N = 2.898 (2 ) Angstrom].