Crystal structures and charge distributions in 2-phenyl-imidazo[1,2-a]-pyridine and two related salts

Abstract

Abstract X-ray structural investigations of 2-phenyl-imidazo[1,2-a]pyridine and two of its salts: 1-methyl-2-phenyl-imidazo[1,2-a]pyridinium iodide and 1-methyl-2-phenyl-6-nitro-imidazo[1,2-a]pyridinium iodide (R = 0.040, 0.032, 0.034 respectively), together with semiempirical calculations of charge distribution, have been carried out. The insertion of nitro-group does not cause any fundamental changes in geometry, but induces changes in the electron density distribution in the bicyclic unit. As a result rather short cation-anion contacts (I … C = 3.52 Å) are observed in structure III.