Molecular Cocrystals of Carboxylic Acids. XII. Structures of the 1 : 1 Adducts of 4-Nitrobenzoic Acid and 3,5-Dinitrobenzoic Acid With N,N'-Bis(1-methylethyl)-6-methylthio-1,3,5-triazine-2,4-diamine (Prometryn)

Abstract

Two 1:1 molecular adducts of the s- triazine herbicide prometryn [N,N′- bis (1-methylethyl)-6-methylthio-1,3,5-triazine-2,4-diamine] with 4-nitrobenzoic acid, [(C₇H₄NO₄)^-(C₁₀H₂₀N₅S)⁺.H₂O] (1), and with 3,5-dinitrobenzoic acid, [(C₇H₃N₂O₆)^-(C₁₀H₂₀N₅S)⁺] (2), have been prepared and characterized. The structure of (1) has been determined by X-ray methods and refined to a residual R 0.055 for 2072 observed reflections. Crystals are monoclinic, space group P2₁/c with Z 4 in a cell of dimensions a 7.191(4), b 28.359(8), c 10.990(6) Ǻ, β 104.75(3)°. The carboxylic acid group protonates a nitrogen of the triazine ring and is involved in a cyclic hydrogen-bonding association with this and with a secondary amine of the side chain [N…O, 2.76, 2.78(1)Ǻ], while the second amine is associated with the lattice water [N…O, 2.90(1)Ǻ]. Spectroscopic methods have been used to confirm the similarity of the molecular associations involving the carboxylic acid groups of the aromatic acids and prometryn in both (1) and (2).