Formation of Benzimidazoisoquinolinium and Benzimidazoisoindolinum Cyclic Systems by the Reaction of 2-(2-Alkynylphenyl)benzimidazoles with Iodine and Iodine-Iodine Interaction Including Halogen Bonding in Their Crystal Structures

摘要

The reaction of 2-(2-alkynylphenyl)benzdimidazoles with molecular iodine constructed 5- and 6 -membered rings as novel organic salts in high yield. The constituted number of ring systems was influenced by the substituent at the triple bond: 6-membered rings were formed from compounds bearing aryl substituents, whereas 5-membered ones were obtained from compounds with hydrogen or alkyl substituents. The products were obtained with triiodide as a counteranion; however, compounds with iodide were also obtainable under certain conditions. We also revealed that they had an iodine iodine interaction included in halogen bonding between an iodo moiety of the cation and a triiodide or iodide of the counteranion. The iodine iodine interaction was formed with greater preference than the electrostatic interaction between the cationic atom and triiodide or iodide.