Gadolinium (Gd) complexes of benzene (C6H6) and (1,3,5,7-cyclooctatetraene) (C8H8) were produced in a laser-vaporization supersonic molecular beam source and studied by single-photon pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy. Adiabatic ionization energies and metal-ligand stretching frequencies were measured for the first time from the ZEKE spectra. Metal-ligand bonding and electronic states of the neutral and cationic complexes were analyzed by combining the spectroscopic measurements with ab initio calculations. The ground states of Gd(C6H6) and [Gd(C6H 6)]+ were determined as 11A2 and 10A2, respectively, with C6v molecular symmetry. The ground states of Gd(C8H8) and [Gd(C 8H8)]+ were identified as 9A 2 and 8A2, respectively, with C8v molecular symmetry. Although the metal-ligand bonding in Gd(C6H 6) is dominated by the covalent interaction, the bonding in Gd(C 8H8) is largely electrostatic. The bonding in the benzene complex is much weaker than that in the cyclooctatetraene species. The strong bonding in Gd(C8H8) arises from two-electron transfer from Gd to C8H8, which creates a strong charge-charge interaction and converts the tub-shaped ligand into a planar form. In both systems, Gd 4f orbitals are localized and play little role in the bonding, but they contribute to the high electron spin multiplicities.
|Number of pages||7|
|Journal||Journal of Physical Chemistry A|
|State||Published - Jan 19 2012|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry