Group III (Sc, Y, and La) metal-(1,3,5,7-cyclo-octatetraene) (COT) complexes were produced in a laser-vaporization molecular beam source and studied by pulsed-field-ionization zero-electron-kinetic-energy (ZEKE) spectroscopy. Adiabatic ionization energies and metal-ligand stretching frequencies were measured from the ZEKE spectra. Metal-ligand bonding and low-lying electronic states of the neutral and ionized complexes were analyzed by combining the spectroscopic measurements with the molecular orbital treatment and density functional theory calculations. The ionization energies and metal-ligand stretching frequencies of these complexes are in the order of Sc>Y>La The ground electronic state of the neutral complexes is 2A1, whereas the ground state of the ions is 1A1. The molecular symmetry is C8ν in both neutral and ionic ground states. Although free COT is a nonaromatic molecule with a tublike structure, coordination of the group III metal atoms converts the tub-shaped molecule into a planar, aromatic structure. This conversion is induced by a two-electron transfer from the metal atoms to the ligand upon the formation of the complexes.
|Journal||Journal of Chemical Physics|
|State||Published - 2009|
Bibliographical noteFunding Information:
We are grateful for the financial support from the Experimental Physical Chemistry Program of the National Science Foundation. We also acknowledge additional support from donors of the Petroleum Research Fund of the American Chemical Society and Kentucky Science and Engineering Foundation.
ASJC Scopus subject areas
- Physics and Astronomy (all)
- Physical and Theoretical Chemistry