Synthesis of Imidazolium/Benzimidazolium Salts and the Preparation of Silver(I) Complex of Bis‐Benzimidazolium Dibromide

The reactions of N‐methyl imidazole with benzyl bromide and N‐isopropyl benzimidazole with either benzyl bromide or 2,4,6‐trimethyl benzyl bromide afforded the expected imidazolium/benzimidazolium salts, respectively. However, the reaction of N‐methyl imidazole/N‐isopropyl benzimidazole with tert‐butyl bromide results in an unexpected 1‐methyl imidazolium/benzimidazolium bromide. The latter products show a very low melting point without decomposition which suggests that they belong to the category of ionic liquids. Further, the treatment of N‐isopropyl imidazole/N‐isopropyl benzimidazole with 1,3‐bis(bromomethyl)‐2,4,6‐trimethylbenzene yielded 1,1′‐di(isopropyl)‐3,3′‐(mesityldimethylene)‐diimidazolium/dibenzimidazolium dibromide. In this paper, the syntheses and the spectroscopic characterizations of all the seven imidazolium/benzimidazolium salts and the synthesis of silver(I) complex of 1,1′‐di(isopropyl)‐3,3′‐(mesityldimethylene)‐dibenzimidazolium dibromide are reported.