ChemInform Abstract: New 3-(2′-Benzimidazolyl)imidazo(1,2-a)pyridinium Mesomeric Betaines. Synthesis and Structure.

Reaction of N-[(2'-benzimidazolyl)methyl]pyridinium salts 2 with isothiocyanates results in a series of 3-(2'-benzimidazolyl)imidazo[1,2-a]pyridinium 2-thiolate derivatives 3 classified as conjugated mesomeric betaines. S-Methylation followed by deprotonation easily converts 3 into a new family of conjugated betaines 5. Semiempirical molecular orbital calculations provide complementary information to the X-ray analysis and experimental dipole moments of both betaines