The spectroscopic study of hydrogen bonding in some 3,3′-derivatives of 2,2′-bipyridyl

Abstract

Four 3,3′-derivatives of 2,2′-bipyridyl have been investigated by multinuclear NMR, IR and X-ray methods. In all cases the weak intramolecular hydrogen bonds between exocyclic nitrogen-containing substituent and pyridine-type ring nitrogen atom were found. In contrast to the previous results the nitrogen chemical shifts of pyridine ring atom do not provide valuable information about hydrogen bond strength. The presence of intramolecular hydrogen bonds were confirmed by nitrogen chemical shifts of exocyclic amino and acetamide groups, deuterium isotope effects in the solid state and IR measurements in both chloroform solution and the solid state. The X-ray structures obtained for asymmetric 3-amino-3′-methylamino and 3,3′-diacetamide derivatives confirmed conclusions made on the base of spectral results.