35Cl and 37Cl Pure Quadrupole Resonance in α-CH2ClCOOH: Hydrogen Bonding and Chlorine Isotope Effect

Abstract

The temperature dependence of the pure nuclear quadrupole resonance of 35Cl and 37Cl in solid α-CH2ClCOOH has been measured from 77 K to 298 K. The NQR spectrum consists of a doublet arising from the two nonequivalent chlorine atoms in the unit cell. The temperature dependence was calculated using the Bayer-Kushida theory which gives a satisfactory fit to the NQR spectra in the temperature range investigated. From the NQR data evidence of an isotope effect was found for both nonequivalent chlorine atoms. The isotope effect depends on the C-Cl bond length and its direction probably on the state of binding of the chlorine atoms. The NQR results and their interpretation are consistent with the crystal structure of α- CH2ClCOOH.