1H and 13C NMR studies of intramolecular hydrogen bonds in substitued 2,6-bis(diethylaminomethyl)phenol di-N-oxides and their monotetrahcloroaurates

Abstract

Abstract Ten substituted 2,6-bis(diethylaminomethyl)phenol di- N -oxides (2,6-DNO) and their monotetrachloroaurates were studied by 1 H and 13 C NMR spectroscopy. With the 2,6-DNO, the chemical shift of the hydrogen-bonded proton demonstrates that equilibria occur betwen the non-polar and polar structures of the intramolecular hydrogen bond (OH ⋯ OH ⇌ O − ⋯ H + ON) and between a homoconjugated intramolecular hydrogen bond (NO ⋯ H + ⋯ ON). With the monotetrahcloroaurates of the 2,6-DNO, an intramolecular hydrogen-bonded system is formed in which a collective proton motion proceeds and which shows large proton polarizability. The 1 H NMR chemical shifts of the hydrogen-bonded protons become first stronger and after a maximum again weaker. The 13 C NMR results prove that this method is a useful tool for studies of molecular hydrogen bonds in which collective proton motion occurs.