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

Molecules

Laure Vendier¹  Lionel Rechignat¹  Dmitry A. Valyaev¹  Alix Sournia-Saquet¹  Mirko Ruamps¹  Vincent César¹  Noël Lugan¹  Stéphanie Bastin¹  Jean-Marie Mouesca²  Vincent Maurel² 

[1]LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France

[2]Université Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France

关键词: redox-active ligands;    N-heterocyclic carbene;    organometallic complexes;    EPR spectroscopy;    DFT calculations;   

DOI  :  10.3390/molecules27123776

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown