Structural, spectroscopic and redox properties of a mononuclear CoII thiolate complex - the reactivity toward S-alkylation: an experimental and theoretical study

Autor: Jacques Pécaut, Nikita Hall, Hervé Vezin, Marcello Gennari, Maylis Orio, Bertrand Gerey, Marie-Noëlle Collomb, Carole Duboc
Přispěvatelé: Département de Chimie Moléculaire - Chimie Inorganique Redox (DCM - CIRE), Département de Chimie Moléculaire (DCM), Université Joseph Fourier - Grenoble 1 (UJF)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Reconnaissance Ionique et Chimie de Coordination (RICC), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 (LASIRE), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Département de Chimie Moléculaire - Chimie Inorganique Redox Biomimétique (DCM - CIRE), Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille Institut (CLIL)
Jazyk: angličtina
Rok vydání: 2012
Předmět:
Zdroj: Dalton Transactions
Dalton Transactions, 2012, 41, pp.12586-12594. ⟨10.1039/C2DT31222K⟩
Dalton Transactions, Royal Society of Chemistry, 2012, 41, pp.12586-12594. ⟨10.1039/C2DT31222K⟩
ISSN: 1477-9226
1477-9234
DOI: 10.1039/C2DT31222K⟩
Popis: The structural, spectroscopic, redox properties and also the reactivity toward S-alkylation of a new mononuclear N2S2 dithiolate CoII complex [CoL] (1), with H2L = 2,2′-(2,2′-bipyridine-6,6′-diyl)bis(1,1-diphenylethanethiol), have been investigated. The X-ray structure of 1 has revealed an unusual distorted square planar geometry for a CoII ion within a thiolate environment. The X-band EPR spectrum of 1 displays a rhombic S = 1/2 signal consistent with a low spin configuration for the d7 CoII ion with a large g-anisotropy (gx = 2.94, gy = 2.32 and gz = 2.01). By pulsed EPR experiments (HYSCORE), two weak hyperfine couplings (hfc) of 3.2 and 2.2 MHz have been measured and attributed respectively to protons and nitrogen nuclei of the bipyridine unit. In addition, another hyperfine coupling (hfc) of 7.5 MHz has been attributed to the cobalt ion. DFT calculations have successfully reproduced the Co and 14N hfc parameters. However, multiconfigurational ab initio calculations were required to predict the g-tensor of 1. The cyclic voltammogram (CV) displays two one-electron metal based processes: a quasi-reversible CoIII/CoII oxidation wave at E1/2 = −0.5 V vs. Fc+/Fc and a quasi-reversible CoII/CoI reduction wave at E1/2 = −1.7 V. 1 reacts with CH3I, generating the mono S-methylated complex, [CoLMeI] (1Me). The X-band EPR spectrum of 1Me displays a typical signal of a high spin (S= 3/2) CoII species. An optimized structure of 1Me, calculated by DFT, is consistent with its EPR and UV-visible spectra. Time dependent density functional theory (TD-DFT) calculations attribute the most prominent features observed in the electronic absorption spectra of 1 and 1Me. The singly occupied MO (SOMO) of 1 shows a notable delocalization of the unpaired electron over the metal (85%) and the ligand, especially over the sulphur atoms (10.5%), indicating a certain degree of covalency for the Co-S bonds. In 1Me, for two of the three SOMOs, the unpaired electron is notably delocalized over the metal (78.5 and 77.6%, respectively) and the ligand (12.5 and 7.8%, respectively over the sulphur of the thiolate function). For the third SOMO, the unpaired electron is mainly localized on the metal (92.2%). There is no electronic density spread on the sulphur atom of the thioether function in any of these SOMOs. The reactivity and the electronic properties of 1 are also compared with those of the analogous [ZnL] and [NiL] complexes.
Databáze: OpenAIRE
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