ANHARMONIC VIBRATIONAL SPECTROSCOPY
FOR TRANSITION METAL COMPLEXES
Camille Latouche
Julien Bloino
Vincenzo Barone
Dimitrios Skouteris
Federico Palazzetti
Alberto Baiardi
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
2
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
3
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)
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
4
Toward quantitative accuracy
Inclusion of solvent effects
Inclusion of anharmonic effects and
of the correct excited-state PES
5
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
6
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
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Harmonic vs Anharmonic frequencies, the case
of Ferrocene
PBE0/#
B3PW91/#
B3LYP/#
PBE0/§
B3PW91/§
B3LYP/§
PBE0/*
B3PW91/*
B3LYP/*
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan
# = m6-31g*/SNSD
§ = m6-31g*/6-31g**
* = Stuttgart/6-311g**
Harm
Anharm
0
20
|Difference vs. Experiment
40
(cm-1)|
8
60
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
Harm
Anharm
0
20
40
|Difference vs. Experiment (cm-1)|
60
9
Harmonic vs Anharmonic frequencies, the case
of Osmocene (I)
CAM/Def2s
PBE0/Def2s
B3PW91/Def2s
B3LYP/Def2s
BP86/Def2s
PBE0/*
B3PW91/*
B3LYP/*
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan
Harm
Anharm
* = Stuttgart/6-311g**
0
20
|Difference vs. Experiment
40
(cm-1)|
60
10
Harmonic vs Anharmonic, the case of
Osmocene (II)
CAM/Def2s
PBE0/Def2s
B3PW91/Def2s
B3LYP/Def2s
BP86/Def2s
PBE0/*
B3PW91/*
B3LYP/*
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan
Harm
Anharm
* = Stuttgart/6-311g**
0
20
|Difference vs. Experiment
40
(cm-1)|
11
60
* = Stuttgart/6-311g**
§ = m6-31g*/6-31g**
# = m6-31g*/SNSD
12
PBE0/#
B3PW91/#
60
B3LYP/#
PBE0/§
B3PW91/§
B3LYP/§
PBE0/*
B3PW91/*
B3LYP/*
CAM/Def2
CAM/Lan
PBE0/Def2
PBE0/Lan
B3PW91/Def2
B3PW91/Lan
B3LYP/Def2
B3LYP/Lan
BP86/Def2
BP86/Lan
|Difference vs. Experiment (cm-1)|
The Case of Ferrocene in detail
Metal
Cp-CH
Global
50
40
30
20
10
0
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
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Thank you for your attention
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