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1. Redox Non-Innocence of the Bridge in Copper(II) Salophen and bis-Oxamato Complexes

Author

De Bellefeuille , D., Orio , M., Barra , A.L, Aukauloo , A., JOURNAUX , Yves, Philouze , C., Ottenwaelder , X., Thomas , F., Department of Chemistry and Biochemistry, Concordia University [Montreal, Canada], Laboratoire national des champs magnétiques intenses - Grenoble ( LNCMI ), Centre National de la Recherche Scientifique ( CNRS ), Service de Bioénergétique, Biologie Stucturale, et Mécanismes ( SB2SM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Biologie Intégrative de la Cellule ( I2BC ), Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ) -Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Institut de Chimie Moléculaire et des Matériaux d'Orsay ( ICMMO ), Université Paris-Sud - Paris 11 ( UP11 ) -Centre National de la Recherche Scientifique ( CNRS ), Institut Parisien de Chimie Moléculaire ( IPCM ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Département de Chimie Moléculaire - Chimie Inorganique Redox Biomimétique ( DCM - CIRE ), Centre National de la Recherche Scientifique ( CNRS ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut de Chimie Moléculaire de Grenoble (ICMG), Concordia University [Montreal], Laboratoire national des champs magnétiques intenses - Grenoble (LNCMI), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UPS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Service de Bioénergétique, Biologie Stucturale, et Mécanismes (SB2SM), Centre National de la Recherche Scientifique (CNRS)-Institut de Biologie Intégrative de la Cellule (I2BC), Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut Parisien de Chimie Moléculaire (IPCM), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Département de Chimie Moléculaire - Chimie Inorganique Redox Biomimétique (DCM - CIRE), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut de Chimie Moléculaire de Grenoble (ICMG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
[ PHYS.PHYS.PHYS-CHEM-PH ] Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], [PHYS.PHYS.PHYS-ATM-PH]Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], [ PHYS.PHYS.PHYS-ATM-PH ] Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

2. Redox noninnocence of the bridge in copper(II) salophen and bis(oxamato) complexes.

Author

de Bellefeuille D, Orio M, Barra AL, Aukauloo A, Journaux Y, Philouze C, Ottenwaelder X, and Thomas F

Subjects
Benzyl Alcohol chemistry, Coordination Complexes chemical synthesis, Electrochemistry, Electron Spin Resonance Spectroscopy, Molecular Structure, Oxamic Acid analogs & derivatives, Oxamic Acid chemistry, Salicylates chemistry, Coordination Complexes chemistry, Copper chemistry, Oxidation-Reduction
Abstract

Two square-planar copper(II) complexes of 1,2-bis(2-hydroxy-3,5-di-tert-butylbenzimino)-4,5-bis(dimethylamino)benzene (1) and N-[4,5-bis(dimethylamino)-2-(oxalylamino)benzene]oxamate (2(2-)) were prepared. The crystal structures of the proligands H2L(1) and Et2H2L(2), as well as the corresponding complexes, are reported. The proligands each display a one-electron-oxidation wave, which is assigned to oxidation of the bis(dimethylamino)benzene moiety into a π radical. Complexes 1 and 2(2-) exhibit reversible one-electron-oxidation waves in their cyclic voltammograms (E1/2(1) = 0.14 and E1/2(2) = 0.31 V for 1 and E1/2(1) = -0.47 V vs Fc(+)/Fc for 2(2-)). The first process corresponds to oxidation of the bis(dimethylamino)benzene central ring into a π radical, while the second process for 1 is ascribed to oxidation of the π radical into an α-diiminoquinone. The one-electron-oxidized species 1(+) and 2(-) exhibit intense visible-near-IR absorptions, which are diagnostic of π radicals. They display a triplet signal in their electron paramagnetic resonance spectra, which stem from magnetic coupling between the ligand-radical spin and the copper(II) spin. The zero-field-splitting parameters are larger for 2(-) than 1(+) because of greater delocalization of the spin density onto the coordinated amidato N atoms. Density functional theory calculations support a π-radical nature of the one-electron-oxidized complexes, as well as S = 1 ground spin states. The electrogenerated 1(2+) comprises a closed-shell diiminoquinone ligand coordinated to a copper(II) metal center. Both 1 and 2 catalyze the aerobic oxidation of benzyl alcohol, albeit with different yields.

Published
2015
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3. Reversible double oxidation and protonation of the non-innocent bridge in a nickel(II) salophen complex.

Author

de Bellefeuille D, Askari MS, Lassalle-Kaiser B, Journaux Y, Aukauloo A, Orio M, Thomas F, and Ottenwaelder X

Subjects
Crystallography, X-Ray, Models, Molecular, Molecular Structure, Organometallic Compounds chemical synthesis, Oxidation-Reduction, Quantum Theory, Nickel chemistry, Organometallic Compounds chemistry, Protons, Salicylates chemistry
Abstract

Substitution on the aromatic bridge of a nickel(II) salophen complex with electron-donating dimethylamino substituents creates a ligand with three stable, easily and reversibly accessible oxidation states. The one-electron-oxidized product is characterized as a nickel(II) radical complex with the radical bore by the central substituted aromatic ring, in contrast to other nickel(II) salen or salophen complexes that oxidize on the phenolate moieties. The doubly oxidized product, a singlet species, is best described as having an iminobenzoquinone bridge with a vinylogous distribution of bond lengths between the dimethylamino substituents. Protonation of the dimethylamino substituents inhibits these redox processes on the time scale of cyclovoltammetry, but electrolysis and chemical oxidation are consistent with deprotonation occurring concomitantly with electron transfer to yield the mono- and dioxidized species described above.

Published
2012
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