Crystal structure and Hirshfeld surface analysis of two organic salts based on 1,3,4-thiadiazole derivatives

During attempts to achieve interaction between 2-amino-5-ethyl-1,3,4-thiadiazole with oxalyl chloride and 5-mercapto-3-phenyl-1,3,4-thiadiazol-2-thione with various diacid anhydrides, we obtained two co-crystals (organic salts), namely, 2-amino-5-ethyl-1,3,4-thiadiazol-3-ium hemioxalate, C4H8N3S+ (.-)0.5C(2)O(4)(2-), (I), and 4-(dimethylamino)pyridin-1-ium 4-phenyl-5-sulfanylidene4,5-dihydro-1,3,4-thiadiazole-2-thiolate, C7H11N2+ (C8H5N2S3)-C-. (-), (II). Both solids were investigated by single-crystal X-ray diffraction and by Hirshfeld surface analysis. An infinite one-dimensional chain along [100] is generated through O-(HO)-O-. . . interactions between the oxalate anion and two 2-amino-5-ethyl1,3,4-thiadiazol-3-ium cations in compound (I), and a three-dimensional supramolecular framework is generated through C-(HO)-O-. . . and pi-pi interactions. In compound (II), an organic salt is formed by a 4-phenyl-5sulfanylidene-4,5-dihydro-1,3,4-thiadiazole-2-thiolate anion and a 4-(dimethylamino)pyridin-1-ium cation, which are combined by an N-(HS)-S-. . . hydrogenbonding interaction, forming a zero-dimensional structural unit. As a result of intermolecular pi-pi interactions, the structural units are combined into a onedimensional chain running along the a-axis direction.