CONFORMATIONAL-ANALYSIS OF THE SODIUM 12-CROWN-4 COMPLEX - PHOTOIONIZATION AND AB-INITIO MOLECULAR-ORBITAL STUDIES/

The molecular complexes formed between sodium atoms and 12-crown-4 mol ecules were generated in a flow reactor and studied with photoionizati on mass spectroscopy. The photoionization threshold energies of these complexes, which are dependent on the complex conformations, were obta ined from the analysis of the photoionization efficiency spectra. Ab i nitio molecular orbital calculations were performed on the possible co nformers of these complexes and their corresponding ionic states. With the help of theoretical calculations, the photoionization threshold e nergy of the C-4 conformer of Na(12-crown-4) was determined to be 3.01 +/- 0.02 eV, and the C-s conformer to be 3.36 +/- 0.04 eV. The photoi onization threshold energy of the Ci conformer was estimated to be 3.8 2 +/- 0.04 eV. The conformation-dependent valence electron spatial dis tributions, bond dissociation energies, and photoionization threshold energies of the Na(12-crown-4) complex could be rationalized and class ified in the framework of the general properties of the complexes form ed between the sodium atoms and Lewis base molecules.