Investigation of the hydrogen bonding in chlorocarboxylate anions using 35Cl quadrupole resonance spectroscopy

Abstract

35 Cl quadrupole resonance frequencies have been measured in a wide range of normal and acid salts of chlorocarboxylic and chlorobenzoic acids. The multiplicity of 35Cl signals and the shifts of the 35Cl frequencies on deuteriation of the acid proton in salts containing the anion [RCO2‥ H ‥ CO2R]– have been used to establish the symmetry of the hydrogen bond. The observed deuteriation shifts can be as large as 0.9 % of the 35Cl frequency in asymmetric hydrogen bonds; they are negligibly small if the hydrogen bond is symmetric.