Synthesis, structure, and tautomerism of formazans that contain 1-aryl-2-benzimidazolyl residues

1,5-Bis(1-aryl-2-benzimidazolyl)-3-methyl- and 1-(p-tolyl)-3-methyl-5-(1-aryl-2-benzimidazolyl)formazans were synthesized. It was shown by IR spectroscopy (from the change in the spectral characteristics of the NH, groups) that the formazans exist in the imino form in solutions in CCl4, whereas a tautomeric equilibrium between the amino and imino forms of the investigated compounds is observed in solutions in CHCl3.