PROTON LOCALIZATION IN ACID-BASE MOLECULAR-SYSTEMS BY NUCLEAR-QUADRUPOLE RESONANCE SPECTROSCOPY

Cl-35-nuclear quadrupole resonance (Cl-35-NQR) spectroscopic studies o f trichloroacetic acid (TCA) complexes with various organic bases (B) of different strength have been performed. The position and energy sta te of the proton in the hydrogen bond are discussed in terms of two mo dels of hydrogen bond assuming one or two minima in the proton potenti al energy curve. The Cl-35-NQR frequencies of protonated trichloroacet ic acid (TCAH+) have been measured. These frequencies are shifted rela tive to TCA frequencies in the opposite direction to the shifts of TCA .B complex frequencies. Electronegativities of the atomic groups, COO- , COO(delta-), COOH and COOH2+ have been determined.