MOLECULAR-COMPLEXES OF POTASSIUM WITH METHANOL AND 1,2-ETHANEDIOL - PHOTOIONIZATION AND AB-INITIO MOLECULAR-ORBITAL STUDIES

The molecular complexes of the potassium atoms with methanol and 1,2-e thanediol were generated in a flow reactor and studied with photoioniz ation mass spectrometry. The photoionization efficiency spectra of the se complexes were measured and the ionization threshold energies were determined by the method of the Watanabe plots. The equilibrium confor mation geometries, the harmonic vibrational frequencies, the bond diss ociation energies, and the ionization potentials of these complexes we re calculated by ab initio molecular orbital methods. The correspondin g ionic states of these complexes were also studied. The photoionizati on threshold energy of the potassium-methanol complex was determined t o be 3.78 +/- 0.02 eV. Supported by the theoretical results, the exper imental photoionization threshold potential of the cyclic form of the potassium-1,2-ethanediol conformers was determined to be 3.40 eV and t he upper bounds of the photoionization threshold potentials for the co nformers with concerted-intramolecular hydrogen bonding and the straig ht-chain conformers were estimated to be 3.60 and 3.67 eV, respectivel y. The bond dissociation energy of the potassium-methanol complex was determined to be 8.3 +/- 1.1 kcal/mol. The interplay of the potassium complexation bonding and the intramolecular hydrogen bonding and its e ffects on both the bonding energies and the ionization potentials of t he conformers were emphasized.