Redox-Switchable Behavior of Transition-Metal Complexes Supported by Amino-Decorated N-Heterocyclic Carbenes

Mirko Ruamps (1) , Stéphanie Bastin (1) , Lionel Rechignat (1) , Alix Sournia-Saquet (1) , Laure Vendier (1) , Noël Lugan (1) , Jean-Marie Mouesca (2) , Dmitry A. Valyaev (1) , Vincent Maurel (2) , Vincent César (1)

1 LCC - Laboratoire de chimie de coordination
2 SYMMES - SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé

The coordination chemistry of the N-heterocyclic carbene ligand IMes(NMe2)2, derived from the well-known IMes ligand by substitution of the carbenic heterocycle with two dimethylamino groups, was investigated with d6 [Mn(I), Fe(II)], d8 [Rh(I)], and d10 [Cu(I)] transition-metal centers. The redox behavior of the resulting organometallic complexes was studied through a combined experimental/theoretical study, involving electrochemistry, EPR spectroscopy, and DFT calculations. While the complexes [CuCl(IMes(NMe2)2)], [RhCl(COD)(IMes(NMe2)2)], and [FeCp(CO)2 (IMes(NMe2)2)](BF4) exhibit two oxidation waves, the first oxidation wave is fully reversible but only for the first complex the second oxidation wave is reversible. The mono-oxidation event for these complexes occurs on the NHC ligand, with a spin density mainly located on the diaminoethylene NHC-backbone, and has a dramatic effect on the donating properties of the NHC ligand. Conversely, as the Mn(I) center in the complex [MnCp(CO)2 ((IMes(NMe2)2)] is easily oxidizable, the latter complex is first oxidized on the metal center to form the corresponding cationic Mn(II) complex, and the NHC ligand is oxidized in a second reversible oxidation wave.

Mots clés: Redox-active ligands; N-heterocyclic carbene; Organometallic complexes; EPR spectroscopy; DFT calculations

Domaines: Chimie de coordination

Mirko Ruamps, Stéphanie Bastin, Lionel Rechignat, Alix Sournia-Saquet, Laure Vendier, et al.. Redox-Switchable Behavior of Transition-Metal Complexes Supported by Amino-Decorated N-Heterocyclic Carbenes. Molecules, 2022, 27 (12), pp.3776. ⟨10.3390/molecules27123776⟩. ⟨hal-03709012⟩