Hydrogen bonding in complexes of heterocyclic N-oxides with halogenoacetic acids. Part IV. Osmometric and nuclear magnetic resonance study of lepidine N-oxide complexes with trifluoroacetic and monochloroacetic acids in toluene at 27 °C

Abstract

N.m.r. spectra and average molecular weights of lepidine N-oxide complexes with trifluoroacetic and monochloroacetic acids have been measured in toluene at 27 °C. The results indicate that the following equilibrium is required to interpret the experimental results: 2(B·HO₂CR)⇌(B·H·B)+(RCO₂·H·O₂CR)^–. The molecular weights are employed to calculate the H-bond shift. Concentration-dependence of the 8-H and 2-H ring resonance of complexes and free base is discussed.