1. Pulsed Field Ionization-Zero Electron Kinetic Energy (PFI-ZEKE) Spectroscopy of Sc-C 6 H 5 X(X=F,CH 3,OH) Complexes Changhua Zhang, Serge A. Krasnokutskia and Dong-Sheng Yang Department of Chemistry, University of Kentucky 06-19-2008

2. Motivation Metal aromatic complexes are of fundamental importance in organometallic chemistry and relevant to chemical catalysis and biological processes. These complexes are prototype models for general understanding of metal interactions with aromatic molecules. Adiabatic ionization energy Vibrational structures Electronic states Metal binding site and strength Substituent effect Sc-C 6 H 6 ( 4 A 1,C 6v ) B. R. Sohnlein, S. Li, and D.-S. Yang, J. Chem. Phys. 123, 214306 (2005)

3. PFI-ZEKE Photoelectron Spectroscopy Set-up Calculations: DFT (B3LYP/6-311+G**) and Franck-Condon (FC) factor calculations

4. PIE Spectra of Sc-C 6 H 5 X Complexes Ionization energies: Sc-C 6 H 5 CH 3 < Sc-C 6 H 5 OH < Sc-C 6 H 5 F

5. Experimental ZEKE spectrum and simulations from 1 A← 2 A transition at 200 K. Sc-C 6 H 5 F (Top view) (Side view) Enantiomers 2 A C 1

6. Sc-C 6 H 5 CH 3 PFI-ZEKE spectrum of Sc-C 6 H 5 CH 3 in Ar Experimental ZEKE spectrum and simulations from 1 A← 2 A transition at 10 K. (Top view) (Side view) Enantiomers 2 A C 1

7. Sc-C 6 H 5 OH PFI-ZEKE spectrum of Sc-C 6 H 5 OH in Ar

8. (Top view) (Side view) + 0.3 kJ/mol s-cis s-trans

10. AIEs (cm -1 ), bond dissociation energies (D 0 +(D 0 )) (kJ/mol), and vibrational frequencies (cm -1 ) ZEKEB3LYP Sc-C 6 H 5 FAIE4298542988 D 0 + (D 0 )188.6(69.6) Out of plane ring distortionν 21 + 552559 Sc-C 6 H 5 F stretchν 24 + 374378 Out of plane ring bendingν 25 + 348351 F-C bendingν 28 + /ν 28 ν 28 + -ν 28 =42ν 28 + -ν 28 =17 Sc-C 6 H 5 CH 3 AIE4116740802 D 0 + (D 0 )224.5(79.4) Out of plane ring distortionν 35 + 476495 Sc-C 6 H 5 CH 3 stretchν 36 + 378 Out of plane ring bendingν 37 + 344349 CH 3 rockν 42 + 134144 Sc-C 6 H 5 OHAIE41477/4155741138/41178 D 0 + (D 0 )217.0(75.9)/216.2(75.6) Out of plane ring distortionν 28 + /570 /580 Sc-C 6 H 5 OH stretchν 32 + 380/380379/379 Out of plane ring bendingν 36 + /140 /120

11. Conclusions For the first time, Sc-C 6 H 5 X(X=F,CH 3,OH) complexes have been studied by ZEKE spectroscopy. Ionization energies: Sc-C 6 H 5 CH 3 < Sc-C 6 H 5 OH < Sc-C 6 H 5 F. Sc-C 6 H 6 is in C 6v point group with triplet ionic state and quartet neutral state. Sc-C 6 H 5 X are in π configuration with 1 A and 2 A as the cationic and neutral ground electronic states, respectively. The benzene ring in Sc-C 6 H 6 keeps flat. The aromatic rings in Sc-C 6 H 5 X show distortion structures that two carbons in each ring displaced toward the metal atom. All complexes have enantiomers. Cis-trans isomers of Sc-C 6 H 5 OH are obtained by ZEKE.

12. Thank you!