YUXIU LEI AND DONG-SHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055.
Scandium complexes of p- and m-terphenyls were prepared in laser-vaporization supersonic molecular beams and studied by pulsed field ionization-zero electron kinetic energy photoelectron spectroscopy and density functional theory calculations. Several initial structures with Sc binding at different phenyl rings and bridging carbon bonds were considered in the calculations. A structure with the six-fold Sc binding at the terminal ring of these terphenyls was identified in our experiments. In both complexes, the ground electronic state of the neutral complexes was determined to be 4A, and that of the corresponding ion was 3A. For Sc-(p-terphenyl), the adiabatic ionization energy of 38838(6) cm-1 and a ring bending frequency of 49 cm-1 was measured for the quartet neutral molecule, and four vibrational frequencies of 354, 309, 77, and 44 cm-1 were identified for the triplet ion. These ion frequencies were assigned to two metal-ligand stretches, a ring torsion, and a ring bend, respectively. For Sc-(m-terphenyl), the adiabatic ionization energy was measured to be 38290(6) cm-1, and seven ion vibrational frequencies were determined to be 436, 377, 355, 330, 303, 279, and 46 cm-1. Similar to the p-terphenyl complex, these ion frequencies were assigned to metal-ligand stretches and ring deformations.