1. ANHARMONIC VIBRATIONAL SPECTROSCOPY FOR TRANSITION METAL COMPLEXES
Camille Latouche
Julien Bloino
Vincenzo Barone
Dimitrios Skouteris
Federico Palazzetti
Alberto Baiardi

2. Outline
Introduction
I – Computed Resonance Raman Spectra of Metal Complexes including Anharmonic and Solvent Effects
II – Benchmark on Frequencies of Metal Complexes including Anharmonic Corrections
Perspectives

3. Introduction Ru derivatives are used in many industrial fields:
Solar Cells
Sensors …
In order to characterize the targeted compounds  Multi-Frequency analyses
Vibrational contributions to electronic transition are rarely taken into account. Vibronic spectra are still rare, especially on metal complexes
Need data at the anharmonic level for many types of compounds, including complexes

4. I- Resonance Raman on [Ru(bpy)3]2+
Our target: [Ru(bpy)3]2+
This compound has been extensively studied both experimentally and theoretically
B3PW91/LANL2DZ + pol./PCM(CH3CN)
Minimum requisite for vibronic spectroscopy
Further refinement
What is mandatory:
DFT Frequency calculation on the optimized Ground State
TD-DFT calculation of Excited State energies and gradients on the optimized Ground State
What is better:
TD-DFT Optimization of the Excited State
TD-DFT Harmonic Frequency calculation on the optimized Excited State
DFT Anharmonic frequency calculation on the optimized Ground State
Scaling of Harmonic Frequencies of the Excited State

5. Toward quantitative accuracy
Inclusion of solvent effects
Inclusion of anharmonic effects and
of the correct excited-state PES

6. First Conclusions
It is possible to reproduce resonance Raman spectra of Metal Complexes accurately
To do so, it is necessary to go beyond the harmonic level and to get more information from the Exc. State.
DFT has become a crucial and effective tool thanks to intensive developments to improve its reliability and efficiency
The anharmonic effects have critical impact on the accuracy
To go further and with other molecules, it is necessary to have more data but beyond the Harmonic level
 Need for a comprehensive Benchmark of frequencies at the Anharmonic level

7. II- Anharmonic Benchmark of Metal Complexes
Need simple molecules
Need well-characterized molecules
Need molecules well studied at both experimental and theoretical levels
Metallocenes seem to be the best candidates to do so
First, we study the C-H vibrations and, in the case of Ferrocene, metal vibration will be discussed
Acronyms used: CAM = CAM-B3LYP
Def2 = DefTZVP Def2s = Def2SVP
LAN = LANL2DZ + polarization

8. Harmonic vs Anharmonic frequencies, the case of Ferrocene
PBE0/#
B3PW91/#
# = m6-31g*/SNSD
B3LYP/#
PBE0/§
B3PW91/§
B3LYP/§
PBE0/*
§ = m6-31g*/6-31g**
B3PW91/*
B3LYP/*
* = Stuttgart/6-311g**
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan

9. Harmonic vs Anharmonic frequencies, the case of Ruthenocene
Preliminary results
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan

10. Harmonic vs Anharmonic frequencies, the case of Osmocene (I)
CAM/Def2s
PBE0/Def2s
B3PW91/Def2s
B3LYP/Def2s
BP86/Def2s
PBE0/*
B3PW91/*
B3LYP/*
* = Stuttgart/6-311g**
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan

11. Harmonic vs Anharmonic, the case of Osmocene (II)
CAM/Def2s
PBE0/Def2s
B3PW91/Def2s
B3LYP/Def2s
BP86/Def2s
PBE0/*
B3PW91/*
* = Stuttgart/6-311g**
B3LYP/*
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan

12. The Case of Ferrocene in detail
|Difference vs. Experiment (cm-1)|
CAM/Def2
PBE0/Lan
PBE0/Def2
CAM/Lan
B3PW91/Lan
B3PW91/Def2
BP86/Lan
BP86/Def2
B3LYP/Lan
B3LYP/Def2
B3LYP/*
B3PW91/*
B3LYP/§
B3PW91/§
PBE0/§
B3LYP/#
B3PW91/#
PBE0/*
PBE0/#
* = Stuttgart/6-311g**
§ = m6-31g*/6-31g**
# = m6-31g*/SNSD

13. Conclusion and Perspectives
DFT and TD-DFT calculations are efficient tools for the rationalization of spectroscopic properties.
Second order vibrational perturbation theory (VPT2) has been used to compute anharmonic IR and Raman spectra. Next, a complete vibronic treatment has been introduced for Resonance Raman spectra.
Solvent effects and anharmonic corrections are mandatory to reach quantitative agreement with experiment concerning both positions (IR, Raman, RR) and intensities (RR) of all peaks
Concerning ligand vibrations, the computational models validated for organic molecules perform a good job also in metallo-organic systems
Vibrations directly involving the metal are more sensitive to the choice of the correlation functional: PW91 seems much better than LYP
B3PW91, associated to a triple-ζ basis set seems to give the best results for the whole spectra

14. Thank you for your attention