%0 Conference Paper %F Oral %T Iron-catalyzed C―C cross-coupling in the absence of additional ligands: active species and off-cycle pathways %+ Catalysis, Synthesis of Biomolecules and Sustainable Development (CSB2D) %+ Laboratoire de Chimie Moléculaire et de Catalyse pour l'Energie (ex LCCEF) (LCMCE) %+ Institut de Biologie Intégrative de la Cellule (I2BC) %+ Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO) %+ Laboratoire de Chimie et Biologie des Métaux (LCBM - UMR 5249) %A Lefèvre, Guillaume %A Rousseau, Lidie %A Dorlet, P. %A Herrero, Christian %A Clémancey, Martin %A Latour, J.-M %< avec comité de lecture %B International Conference on Coordination Chemistry %C Sendai, Japan %8 2018-07-30 %D 2018 %Z Chemical Sciences/Material chemistryConference papers %X Iron-catalyzed cross-coupling between a Grignard reagent RMgX and an electrophile R'─X was discovered by Kochi in the 1970s and witnessed recent improvements. This transformation can be carried out using simple iron salts such as FeCl$_2$ , FeCl$_3$ or Fe(acac)$_3$ in the absence of additional ligand. However, these systems lead to short-lived reactive species, making in-situ mechanistic analysis challenging. By means of Mössbauer, cw-and pulse-EPR spectroscopies, we demonstrated that two arene-stabilized Fe$^0$ and Fe$^I$ resting states were obtained by reduction of the precursor in toluene (Fig. 1a). Analysis of the bulk revealed that the ($\eta^4$-C$_6$H$_5$Me)$_2$Fe$^0$ complex catalyzes efficiently aryl-heteroaryl coupling, via a Fe$^0$ /Fe$^{II}$ cycle (Fig. 1b). Preliminary results moreover show that transient tris(aryl) species such as [Ph$_3$ Fe$^{II}$ ]-are key intermediates in the formation of the lower oxidation states. Fe$^0$ and Fe$^I$ are respectively afforded by 2-electron reductive elimination and by redox disproportionation of the +II ox. state. %G English %2 https://cea.hal.science/cea-02340033/document %2 https://cea.hal.science/cea-02340033/file/Lefevre_ICCC2018.pdf %L cea-02340033 %U https://cea.hal.science/cea-02340033 %~ CEA %~ UGA %~ CNRS %~ UNIV-PSUD %~ IRTSV-CBM %~ PUBNIMBE %~ INC-CNRS %~ IRAMIS-NIMBE %~ CEA-UPSAY %~ I2BC %~ UNIV-PARIS-SACLAY %~ UNIV-PSUD-SACLAY %~ CEA-UPSAY-SACLAY %~ JOLIOT %~ CEA-DRF %~ BIG %~ IRIG %~ CEA-GRE %~ TEST-HALCNRS %~ UGA-COMUE %~ GS-ENGINEERING %~ IRAMIS %~ GS-CHIMIE %~ GS-PHYSIQUE %~ GS-BIOSPHERA %~ GS-HEALTH-DRUG-SCIENCES %~ INSTITUT-SCIENCES-LUMIERE %~ TEST2-HALCNRS %~ ICMMO