MOLECULAR COCRYSTALS OF CARBOXYLIC-ACIDS - XXVIII - NITROSUBSTITUTED CARBOXYLIC-ACIDS WITH LEWIS-BASES - THE CRYSTAL-STRUCTURES OF THE ADDUCTS OF 3,5-DINITROBENZOIC ACID WITH N-METHYLANILINE (1 1), (4-NITROPHENYL)ACETIC ACID WITH CYCLOHEXANE-1,4-DIAMINE (2/1), AND 5-NITROSALICYLIC ACID WITH 2-IMIDAZOLIDONE (2/1)/

A number of molecular adducts of nitro-substituted aromatic acids with Lewis bases have been prepared and characterized by infrared spectros copy and in three cases by X-ray diffraction methods. These three comp ounds are the adducts of: 3,5-dinitrobenzoic acid (dnba) with N-methyl aniline (nma), [(dnba)(-)(nma)(+)] (1); (4-nitrophenyl)acetic acid (4- npa) with cyclohexane-1,4-diamine (dach), [(4-npa)(2)(2-)(dach)(2+)] ( 4); 5-nitrosalicylic acid (5-nsa) with 2-imidazolidone (idaz), [(5-nsa )(2)(idaz)] (5). Other compounds are the adducts of 3,5-dinitrobenzoic acid with 2,6-dimethylpyridine (dmp), [(dnba)(dnba)(-)(dmp)(+)] (2), and with 1-methylpyrrole-2-carboxylic acid (cmp), [(dnba)(-)(cmp)(+)] (3). Compounds (1) and (3) have 1:1 stoichiometry, while (2), (4) and (5) are 2:1 adducts. Proton transfer occurs in most examples [complex (5) is the exception].