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Ruamps M, Bastin S, Rechignat L, Sournia-Saquet A, Vendier L, Lugan N, Mouesca JM, Valyaev DA, Maurel V, César V. Redox-Switchable Behavior of Transition-Metal Complexes Supported by Amino-Decorated N-Heterocyclic Carbenes. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123776. [PMID: 35744903 PMCID: PMC9227367 DOI: 10.3390/molecules27123776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 11/16/2022]
Abstract
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.
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Affiliation(s)
- Mirko Ruamps
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Stéphanie Bastin
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Lionel Rechignat
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Alix Sournia-Saquet
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Laure Vendier
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Noël Lugan
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Jean-Marie Mouesca
- Université Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France;
| | - Dmitry A. Valyaev
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
- Correspondence: (D.A.V.); (V.M.); (V.C.)
| | - Vincent Maurel
- Université Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France;
- Correspondence: (D.A.V.); (V.M.); (V.C.)
| | - Vincent César
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
- Correspondence: (D.A.V.); (V.M.); (V.C.)
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Brousses R, Maurel V, Mouesca JM, César V, Lugan N, Valyaev DA. Half-sandwich manganese complexes Cp(CO) 2Mn(NHC) as redox-active organometallic fragments. Dalton Trans 2021; 50:14264-14272. [PMID: 34553709 DOI: 10.1039/d1dt02182f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Oxidation of the half-sandwich MnI complexes Cp(CO)2Mn(NHC) bearing dialkyl-, arylalkyl- and diarylsubstituted N-heterocyclic carbene ligands (NHC = IMe, IMeMes, IMes) affords the corresponding stable MnII radical cations [Cp(CO)2Mn(NHC)](BF4) isolated in 92-95% yield. Systematic X-ray diffraction studies of the series of MnI and MnII NHC complexes revealed the expected characteristic structural changes upon oxidation, namely the elongation of the Mn-CO and Mn-NHC bonds as well as the diminution of the OC-Mn-CO angle. ESR spectra of [Cp(CO)2Mn(IMes)](BF4) in frozen solution (CH2Cl2/toluene 1 : 1, 70 K) allowed the identification of two conformers for this complex and their structural assignment using DFT calculations. The stability of these NHC complexes in both metal oxidation states, moderate oxidation potentials and the ease of detection of MnII species by a variety of spectroscopic techniques (UV-Vis, IR, paramagnetic 1H NMR, and ESR) make these compounds promising objects for applications as redox-active organometallic fragments.
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Affiliation(s)
- Rémy Brousses
- LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France.
| | - Vincent Maurel
- Univ. Grenoble Alpes, CEA, CNRS, INAC, SyMMES, F-38000 Grenoble, France.
| | - Jean-Marie Mouesca
- Univ. Grenoble Alpes, CEA, CNRS, INAC, SyMMES, F-38000 Grenoble, France.
| | - Vincent César
- LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France.
| | - Noël Lugan
- LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France.
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Romain C, Bellemin-Laponnaz S, Dagorne S. Recent progress on NHC-stabilized early transition metal (group 3–7) complexes: Synthesis and applications. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213411] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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