Synthetic organometallic chemistry and homogeneous catalysis: Defluorination of PFAs with alkaline-earth catalysis

Research project
The alkaline earth metals (= Ae) calcium, strontium and barium are attracting interest as abundant and innocuous s-block alternatives to expensive and more toxic transition metals in catalysis. Ae molecular catalysts are now used in a plethora of catalysed organic transformations, and their unique reactivity features make them ideal complement to traditional d-block systems. Our group has been involved for 15 years in this area of research, and has made several key contributions to the field.

Modern society is growing acutely aware of long-lasting toxicity issues, towards both land soil and human body, associated to per- and polyfluorinated alkyl substances, the infamous “PFAs” that have been dubbed “forever chemicals”. Research on PFAs toxicity has raised concerning alarms about their environmental persistence and accumulation in blood serum and tissues. As a result, organofluorine contamination is one of the most pressing environmental issues. Current efforts focus on physical and chemical means, but effective methods to remedy this situation are still elusive. We believe that our research group has the experience and know-how to make an impact on the field, and this funded, 3-year PhD research project will be a step in this direction. We aim to synthesise well-defined complexes of the large alkaline earths (and, among these, most prominently calcium and strontium that exhibit particular affinity for fluorine) that can catalyse the defluorination of PFAs.

In this context, the three objectives of the PhD project are:
1) With the help of specific organoligands prepared for the purpose, to design and synthesise new molecular calcium and strontium complexes that will be able to activate and, ultimately, cleave C–F bonds. The targeted complexes will be charge-neutral or cationic, depending on the needs;
2) Investigate the stoichiometric reactivity of the new Ae complexes towards benchmark per- or polyfluorinated alkyl substances, hydrosilanes, and a combination of these reactants;
3) Extend the reactivity delineated above into efficient catalytic cycles that will enable effective defluorination of selected PFA compounds.

The project involves a large amount of synthetic organometallic chemistry and homogeneous catalysis with highly air-sensitive compounds, that will require to work under inert atmosphere. The preparation of the ligands will entail a flair for organic chemistry. Once prepared and characterised by conventional methods (NMR spectroscopy in solution, X-ray diffraction crystallography, FTIR, etc.), the new metal complexes will be utilised in homogenous catalysis for C–F bond activation. Understanding the intimate nature of the chemical bonding, structure, stability and reactivity of these complexes will be a key aspect, and DFT investigations will be performed during the project.

Specificity of the PhD position
The full research grant is already secured for the 36-month project. The PhD will be conducted at the University of Rennes under the supervision of Dr Yann SARAZIN (CNRS Research director) and Prof Jean-François CARPENTIER (University of Rennes). (S)He must be to the idea of working in a multi-cultural laboratory. A very good command of English is compulsory; some knowledge of French will also be an advantage. The recruited PhD student will learn an array of soft skills, in addition to the usual scientific skills expected from a PhD training in chemical sciences. (S)He will graduate and gain a PhD degree from the University of Rennes. The student will receive the standard salary for a University of Rennes PhD student (doctoral contract; gross salary 2300 € per month, ca. 1800 € net per month) and will also benefit from the social assets and healthcare of all university staff members.

Selected references related to the project

Barium-catalysed dehydrocoupling of terminal alkynes and hydrosilanes.
S. Mohan, E. Clot, M. Cordier, J.-F. Carpentier, Y. Sarazin, ChemistryEurope 2026, ASAP article. DOI: 10.1002/ceur.202500401

Investigating di-n-butylcalcium.
G. Duneş, M. Hédouin, C. Bastien, S. Kahlal, M. Cordier, W. Erb, F. Mongin, J.-Y. Saillard, H. Oulyadi, Y. Sarazin, ChemistryEurope 2025, 3, e202500196. DOI: 10.1002/ceur.202500196.
Highlighted in ChemistryViews

Barium phosphidoboranes and related calcium complexes.
G. Duneş, P. M. Chapple, S. Kahlal, T. Roisnel, J.-F. Carpentier, J.-Y. Saillard, Yann Sarazin, Dalton Trans. 2024, 53, 6892-6905. DOI: 10.1039/d4dt00487f

Metal-metal bonded alkaline-earth distannyls.
P. M. Chapple, J. Cartron, G. Hamdoun, S. Kahlal, M. Cordier, H. Oulyadi, J.-F. Carpentier, J.-Y. Saillard, Y. Sarazin. Chem. Sci. 2021, 12, 7098-7114, DOI: 10.1039/D1SC00436K

Bis(imino)carbazolate: a master key for barium chemistry.
P. M. Chapple, S. Kahlal, J. Cartron, T. Roisnel, V. Dorcet, M. Cordier, J.-Y. Saillard, J.-F. Carpentier, Y. Sarazin. Angew. Chem. Int. Ed. 2020, 59, 9120-9126 (Hot paper). DOI: 10.1002/anie.202001439
Highlighted in ChemistryViews

Low-coordinate barium boryloxides: synthesis and dehydrocoupling catalysis for the production of borasiloxanes.
E. Le Coz, V. Dorcet, T. Roisnel, S. Tobisch, J.-F. Carpentier, Y. Sarazin, Angew. Chem. Int. Ed. 2018, 57, 11747-11751 (Hot paper). DOI: 10.1002/anie.201807297

Research facilities
The PhD student will work in an internationally renowned group, whose modern laboratory is equipped with all facilities to carry out the proposed air-sensitive organometallic chemistry: individual benches and fume hoods, glove boxes, drying columns, access to analytical instruments, etc. The student will have his/her own dedicated desk in an office, and a PC endowed with all necessary licensed software. The project leaders have a long experience in the proposed field of investigations.

The University of Rennes promotes gender equality in recruitment and career progression.
The PhD will start on September 1, 2026, or as soon as possible after this. Applicants must hold a Master’s degree in molecular chemistry. We are seeking a dynamic, highly motivated student with a strong affinity for organometallic chemistry and catalysis. Previous experience in these fields is a mandatory requirement. An interest in quantum mechanics (DFT) will be an advantage but is not compulsory. The hired student must be able to work in relative autonomy and demonstrate the capacity to bring his/her own input to the project. A very good command of English is compulsory; some knowledge of French will also be an advantage.