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, C(11)H(13)FN(3) (+)·I(−), (1), 1-isopropyl-4-(4-methyl­phen­yl)-1,2,4-triazol-1-ium iodide, C(12)H(16)N(3) (+)·I(−), (2), 1-isopropyl-4-phenyl-1,2,4-triazol-1-ium iodide, C(11)H(14)N(3) (+)·I(−), (3), and 1-methyl-4-phenyl-1,2,4-triazol-1-ium iodide, C(9)H(10)N(3) (+)·I(−), (4), contain one cation and one iodide ion, whereas in 1-benzyl-4-phenyl-1,2,4-triazol-1-ium bromide monohydrate, C(15)H(14)N(3) (+)·Br(−)·H(2)O, (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.