Investigation of ligand electronic effects on iron
cyclopentadienyl complexes using photoelectron
spectroscopy

Lyna Bourehil, Gustavo A Garcia, Denis Lesage, Yves Gimbert, Jean-Luc

Renaud, Leo Bettoni, Nicolas Joly, Sylvain Gaillard, Héloïse Dossmann

► To cite this version:

Lyna Bourehil, Gustavo A Garcia, Denis Lesage, Yves Gimbert, Jean-Luc Renaud, et al. Investigation of ligand electronic effects on iron cyclopentadienyl complexes using photoelectron spectroscopy. Journées Plénières 2022 GDR EMIE, Jun 2022, Dunkerque, France. . hal-04169962

HAL Id: hal-04169962

https://hal.science/hal-04169962

Submitted on 24 Jul 2023

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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
## Introduction

* This project aims to study the electronic effects of several $Fe(CO)_3L^{[1]}$ complexes, because the ligands bound to the metal center are able to orientate the reactivity of the complex through their steric and electronic effects$^{[2]}$. This was achieved using a gas phase approach based on photoelectron spectroscopy performed on the DESIRS$^{[3]}$ beamline of the SOLEIL synchrotron. The rationalization of the electronic effects of the ligand can then be obtained from the analysis of the ionization energies and the Fe-CO dissociation energies selected.

## Experiment

* Ionisation of the gas-phase complexes using synchrotron radiation.

<figure><img src="image_2.png" /><figcaption>**Figure 2a.** Thermodesorption of aerosols.</figcaption></figure>

<figure><img src="image_3.png" /><figcaption>**Figure 2b.** Home made oven installed in the jet chamber.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>**Figure 3.** Experimental device showing the coupling of the DESIRS beamline to the i2PEPICO spectrometer DELICIOUS III.</figcaption></figure>

## Theory

* Electronic structure calculations : PBE0/Def2-TZVP using the GAUSSIAN 09 software.

* Ionisation energy were computed with the IP-tuned LC-ωPBEh functional with the same basis set.$^{[4]}$

* Fe-L bond description : decomposition (EDA) scheme coupled to Natural Orbital for Chemical Valence (NOCV) analysis at the BP86/TZ2P(ZORA)$^{[5]}$ level of theory using the ADF software.

## Kinetic Modeling

* RRKM statistical model using MassKinetics software$^{[6]}$

$$k(E) = \frac{\sigma N^{\#}(E - E_0)}{h\rho(E)}$$

$E$ = internal energy

$E_0$ = critical energy

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>

* Kinetic Shift (KS)$^{[7]}$

* $KS = E_{app} - E_0$

* Depends on Size, Time, $E_0$ & $\Delta S$

<figure><img src="image_7.png" /><figcaption>**Figure 1.** Structure of the synthesised organometallic iron complexes</figcaption></figure>

## Results

* Slow PhotoElectron Spectra (SPES)

* Breakdown diagram

<figure><img src="image_8.png" /><figcaption>**Figure 4.** SPES of Fe4. Red sticks represent the calculated ionization energies of the molecular orbitals of the neutral complexes.</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>**Figure 5.** Breakdown diagram of Fe4 recorded in the 7.7 - 15.0 eV energy range and obtained with a 100 meV energy resolution.</figcaption></figure>

## Conclusion

* Vaporisation of thermally stable or unstable real complexes with low quantities.

* SPES provide access to the electronic structure of the complexes which showed a great agreement with the theory

* The tendency observed in the adiabatic ionisation energy is in correlation with the reaction yields of each catalyst complex.

* The first CO loss of the complexes did not show any selectivity and no trend effect was observed.

<caption>**Table 1.** Experimental and Calculated Adiabatic and Vertical Ionization Energies of the iron Complexes (in eV).</caption>

<table><caption>**Table 2.** Experimental and calculated BDEs of the studied complexes in (eV)</caption><thead><tr><th rowspan="2"></th><th colspan="2">IE<sub>ad</sub></th><th colspan="2">IE<sub>vert</sub></th></tr><tr><th>exp</th><th>calc</th><th>exp</th><th>calc</th></tr></thead><tbody><tr><th>Fe1</th><td>7.20 ± 0.03</td><td>7.29</td><td>7.68 ± 0.03</td><td>7.68</td></tr><tr><th>Fe2</th><td>7.59</td><td>7.59</td><td>8.25</td><td>7.67</td></tr><tr><th>Fe3</th><td>7.49</td><td>7.57</td><td>8.13</td><td>7.95</td></tr><tr><th>Fe4</th><td>6.52</td><td>6.59</td><td>7.01</td><td>7.06</td></tr><tr><th>Fe5</th><td>7.82</td><td>7.65</td><td>8.18</td><td>7.92</td></tr></tbody></table>

<table><thead><tr><th rowspan="2"></th><th colspan="2">BDE first CO loss</th><th colspan="2">BDE second CO loss</th></tr><tr><th>exp</th><th>calc</th><th>exp</th><th>calc</th></tr></thead><tbody><tr><th>Fe1</th><td>0.92 ± 0.10</td><td>0.84</td><td>1.17 ± 0.11</td><td>1.30</td></tr><tr><th>Fe2</th><td>0.80</td><td>0.82</td><td>1.14</td><td>1.30</td></tr><tr><th>Fe3</th><td>0.40</td><td>0.50</td><td>0.83</td><td>1.09</td></tr><tr><th>Fe4</th><td>0.87</td><td>0.93</td><td>0.90</td><td>1.46</td></tr><tr><th>Fe5</th><td>0.99</td><td>0.96</td><td>1.24</td><td>1.34</td></tr></tbody></table>

## References

1. (a) Org. Lett., 2019, 21, 3057-3061. (b) Chemistry-A European Journal, 2013, 19, 17881-17890.
2. (a) Japan. J Synchrotron Radiat, 2012, 19, 508-520.
4. (a) Inc.: Wallingford, CT, USA, 2013. (b) The Journal of chemical physics, 1996, 105, 9982-9985.
5. (c) The Journal of Chemical Physics, 1994, 100, 5829-5835.
6. J. Mass Spectrom., 1996, 31, 445-463.
7. Mass Spectrom. Rev., 1982, 1, 309-348.