New azaheterocyclic aromatic diphosphonates for hybrid materials for fuel cell applications

Abstract

New azaheterocyclic aromatic diphosphonate derivatives of benzimidazole and benzotriazole were synthesized by nickel-catalyzed Arbuzov reaction of 4,7-dibromo-2,1,3-benzothiadiazole with triethyl phosphite, followed by reductive sulfur extrusion reaction and cyclization. This new strategy allowed us to obtain these compounds with high efficiency, with the generation of these azaheterocyclic aromatic diphosphonate derivatives in good to excellent yields, since these compounds could not be synthesized by direct cross-coupling reactions catalyzed by palladium or nickel. All compounds were characterized by NMR, IR spectroscopy and mass spectrometry (low and high resolution). NMR studies of compound 9 showed the presence of only one tautomeric form, on the NMR time scale, in different solvents and at different concentrations.