Crystal structures of five 1-alkyl-4-aryl-1,2,4-triazol-1-ium halide salts

The asymmetric units for the salts 4-(4-fluorophenyl)-1-isopropyl-1,2,4-triazol-1-ium iodide, C11H13FN3+·I−, (1), 1-isopropyl-4-(4-methylphenyl)-1,2,4-triazol-1-ium iodide, C12H16N3+·I−, (2), 1-isopropyl-4-phenyl-1,2,4-triazol-1-ium iodide, C11H14N3+·I−, (3), and 1-methyl-4-phenyl-1,2,4-triazol-1-ium iodide, C9H10N3+·I−, (4), contain one cation and one iodide ion, whereas in 1-benzyl-4-phenyl-1,2,4-triazol-1-ium bromide monohydrate, C15H14N3+·Br−·H2O, (5), there is an additional single water molecule. There is a predominant C—H...X(halide) interaction for all salts, resulting in a two-dimensional extended sheet network between the triazolium cation and the halide ions. For salts with para-substitution on the aryl ring, there is an additional π–anion interaction between a triazolium carbon and iodide displayed by the layers. For salts without the para-substitution on the aryl ring, the π–π interactions are between the triazolium and aryl rings. The melting points of these salts agree with the predicted substituent inductive effects