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29 results on '"Grégory Nocton"'

1. Understanding the Multiconfigurational Ground and Excited States in Lanthanide Tetrakis Bipyridine Complexes from Experimental and CASSCF Computational Studies

Author

Laurent Maron, Richard A. Andersen, Grégory Nocton, Corwin H. Booth, J. I. Amaro-Estrada, Robert L. Halbach, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Laboratoire de chimie moléculaire (LCM), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), University of California [Berkeley], University of California-University of California, Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)

Subjects
Lanthanide, 010405 organic chemistry, Electronic structure, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Magnetic susceptibility, 0104 chemical sciences, Square antiprism, Inorganic Chemistry, Bipyridine, chemistry.chemical_compound, Crystallography, chemistry, Excited state, Molecular orbital, Physical and Theoretical Chemistry, Isostructural
Abstract

International audience; An alternative synthesis for M(κ2-bipy)4 (M = La, Ce) and [Li(thf)4][M(κ2-bipy)4] (M = Tb, Dy) and the crystal structures for M = La, Ce, and Tb are described. The isomorphous and isostructural neutral molecules, M = La and Ce, are polymeric in the solid-state, as are those of M = Sm and Eu, which were reported in earlier work. The polymeric network is built from eight coordinate units whose geometry in all four cases is that of a square prism. The known molecules, M = Yb and Lu, are also polymeric, but the eight coordinate units have dodecahedral geometries. The structure of the anions in the separated ion pair, [Li(thf)4][M(κ2-bipy)4], in which Tb is reported in this work and Lu is known, are monomeric with geometries that are between that of a square antiprism and a dodecahdron. The electronic structure, from CASSCF multireference quantum mechanical calculations, shows that the electronic ground states for M = La and Lu are multiconfigurational spin doublets and those for the M = Ce and Yb are multiconfigurational spin triplets. This is confirmed by magnetic susceptibility studies as a function of temperature that are consistent with the metals (La, Ce, Sm, Tb, Dy, Yb, and Lu) being trivalent, as are the LIII-edge XANES spectra (Ce, Yb), and divalent for Eu. The multiconfigurational nature of the ground states, developed from CASSCF molecular orbital calculations, renders a single Lewis structure and a single reference molecular orbital representation misleading. The results from the multireference calculations are extended to the other lanthanide molecules and are the genesis of a new model for understanding the magnetic properties of these molecules.

Published
2019
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2. Influence of a Lanthanide Ion on the Ni Site of a Heterobimetallic 3d–4f Mabiq Complex

Author

Stuart A. J. Boyce, Jules Moutet, Grégory Nocton, Corinna R. Hess, Lukas Niederegger, Thomas Simler, Laboratoire de chimie moléculaire (LCM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
Lanthanide, 010405 organic chemistry, Chemistry, Ligand, 010402 general chemistry, 01 natural sciences, Article, 0104 chemical sciences, Ion, Inorganic Chemistry, Crystallography, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, Bimetallic strip, ComputingMilieux_MISCELLANEOUS
Abstract

This work presents the synthesis and characterization of a 3d-4f bimetallic complex based on the redox-active macrocyclic biquinazoline ligand, Mabiq. The mixed Yb-Ni complex, [(Cp*)(2)Yb(Mabiq)Ni]BArF (3), was synthesized upon reaction of [Ni(II)(Mabiq)]BArF (2) with Cp*(2)Yb(II)OEt(2). The molecular structures of 3 and its sister complex, [(Cp*)(2)Yb(Mabiq)Ni][(Cp*)(2)Yb(OTf)(2)] (1), confirmed the presence of a Yb(III) center and a reduced Ni-Mabiq unit. Spectroscopy (absorption and NMR), cyclic voltammetry and magnetic susceptibility studies were employed to analyze the electronic structure of 3, which is best described by the [(Cp*)(2)Yb(III)(Mabiq(•))Ni(II)](+) formulation. Notably, the ligand centered radical is delocalized over both the diketiminate and bipyrimidine units of the Mabiq ligand. The magnetic susceptibility and variable temperature NMR studies for 3 denote coupling between the Ni-Mabiq site and the peripheral Yb center – previously unobserved in 3d-3d Mabiq complexes. The complex nature of the exchange interactions is highlighted by the multiconfigurational ground state for 3, comprising nearly degenerate singlet and triplet states.

Published
2021
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3. Intermediate Valence States in Lanthanide Compounds

Author

Nolwenn Mahieu, Grégory Nocton, Maxime Tricoire, Thomas Simler, Laboratoire de chimie moléculaire (LCM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
Lanthanide, spectroscopy, Valence (chemistry), 010405 organic chemistry, Chemistry, Organic Chemistry, theoretical computations, Theoretical models, General Chemistry, 010402 general chemistry, 01 natural sciences, Catalysis, Article, 0104 chemical sciences, Chemical physics, intermediate valence, Electronic effect, [CHIM]Chemical Sciences, lanthanides, Spectroscopy, organometallics
Abstract

Over more than 50 years, intermediate valence states in lanthanide compounds have often resulted in unexpected or puzzling spectroscopic and magnetic properties. Such experimental singularities could not be rationalised until new theoretical models involving multiconfigurational electronic ground states were established. In this minireview, the different singularities that have been observed among lanthanide complexes are highlighted, the models used to rationalise them are detailed and how such electronic effects may be adjusted depending on energy and symmetry considerations is considered. Understanding and tuning the ground-state multiconfigurational behaviour in lanthanide complexes may open new doors to modular and unusual reactivities.

Published
2020
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4. Small molecule activation with divalent samarium triflate: a synergistic effort to cleave O2

Author

Elisa Louyriac, Grégory Nocton, Carine Clavaguéra, Mathieu Xémard, Laurent Maron, and Marie Cordier

Subjects
chemistry.chemical_classification, Lanthanide, 010405 organic chemistry, Salt (chemistry), chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Small molecule, 0104 chemical sciences, Divalent, Inorganic Chemistry, Samarium, Samarium triflate, chemistry, Cleave, Reductive cleavage, Polymer chemistry
Abstract

The divalent samarium triflate salt does not react with CO2 or water, but does react with traces of O2 or N2O to form a tetrameric bis-oxo samarium motif. The reaction with O2 is a 4e− reductive cleavage where the electrons are coming from four different samarium centers. This highlights a rare synergistic effect for cleaving O2, which has no precedent in divalent lanthanide complexes. Additionally, the addition of CO2 to the tetrameric bis-oxo intermediate leads to the formation of a tetrameric bis-carbonate samarium triflate. Thus, the concomitant reaction of CO2 with traces of O2 leads to the same bis-carbonate tetrameric assembly.

Published
2018
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5. Reductive Disproportionation of CO2 with Bulky Divalent Samarium Complexes

Author

Violaine Goudy, Augustin Braun, Grégory Nocton, Christos E. Kefalidis, Mathieu Xémard, Laurent Maron, Marie Cordier, Carine Clavaguéra, Elisa Louyriac, Louis Ricard, Maxime Tricoire, and Ludovic Castro

Subjects
chemistry.chemical_classification, 010405 organic chemistry, Dimer, Organic Chemistry, Inorganic chemistry, chemistry.chemical_element, Disproportionation, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, 0104 chemical sciences, 3. Good health, Divalent, Adduct, Inorganic Chemistry, Samarium, Solvent, chemistry.chemical_compound, chemistry, Pyridine, Physical and Theoretical Chemistry, Diethyl ether
Abstract

The base-free divalent samarium complex Cptt2Sm (1; Cptt = 1,3-(tBu)2(C5H3)) has been synthesized in diethyl ether by salt metathesis of SmI2. Crystals of 1 suitable for X-ray study have been obtained by sublimation at 116 °C under reduced pressure. The dissolution of 1 in thf and pyridine solution leads to the solvent adducts Cptt2Sm(thf)2 (3) and Cptt2Sm(py) (4), respectively, while drying 3 under reduced pressure yields CpttSm(thf) (5). The reaction of CO2 with the base-free divalent samarium complexes Cptt2Sm (1) and Cpttt2Sm (2; Cpttt =1,2,4-(tBu)3(C5H2)) leads to the clean formation of bridged carbonate samarium dimers [Cpttt2Sm]2(μ-CO3) (7) and [Cptt2Sm]2(μ-CO3) (8). This is indicative of the reductive disproportionation of CO2 in both cases with release of CO. This contrasts with the formation of the oxalate-bridged samarium dimer reported from the reaction of CO2 with the Cp*2Sm(thf)2 complex. Otherwise, the reaction with CO does not proceed with the bulky complexes, while traces of O2 have led t...

Published
2017
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6. Redox activity of a dissymmetric ligand bridging divalent ytter-bium and reactive nickel fragments

Author

Jules Moutet, Ding Wang, Maxime Tricoire, Grégory Nocton, Valeriu Cemortan, Laboratoire de chimie moléculaire (LCM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
chemistry.chemical_classification, Lanthanide, 010405 organic chemistry, Ligand, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Article, 0104 chemical sciences, Divalent, Inorganic Chemistry, Nickel, Crystallography, chemistry.chemical_compound, Electron transfer, Deprotonation, chemistry, Moiety, [CHIM]Chemical Sciences, Homoleptic
Abstract

International audience; The reaction of a reactive nickel dimethyl 1 bearing a redox-active, dissymmetric ligand, which is obtained by deprotonation of 2-pyrimidin-2-yl-1H-benzimidazole (Hbimpm) with a divalent lanthanide complex, Cp* 2 Yb(OEt 2), affords an unprecedented, trimeric 2 with C(sp 3)-C(sp 3) bond formation between two ligands in an exo position. Meanwhile, the transient, dimeric species 3 can be isolated with the same ligand coupling fashion, however, with a drastic distorsion angle of the bimpm ligand and reactive NiMe 2 fragment, revealing the possible mechanism of this rearrangement. A much more stable dimeric congener, 5, with an exo ligand coupling, is synthesized in the presence of 18-crown-6, which captures the potassium counter ion. The CC coupling formation between two bimpm ligands results from the effective electron transfer from divalent lanthanide fragments. Without the divalent lanthanide, the reductive coupling occurs on a different carbon of the ligand, nicely showing the modulation of the spin density induced by the presence of the lanthanide ion. The electronic structures of these complexes are investigated by magnetic study (SQUID), indicating a 2 F 7/2 ground state for each ytterbium in all the heterometallics. This work firstly reports ligand coupling reactivity in a redox-active, yet dissymmetric system with divalent organolanthanides, and the reactive nickel moiety can impact the intriguing transition towards a stable homoleptic, trinulear lanthanide species.

Published
2020
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7. Atom economical coupling of benzophenone and N-heterocyclic aromatics with SmI 2

Author

Grégory Nocton, Nicolas Casaretto, Arnaud Jaoul, Carine Clavaguéra, Laurent Maron, Yan Yang, Institut de Chimie Physique (ICP), Institut de Chimie du CNRS (INC)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Reaction mechanism, 010405 organic chemistry, Phenanthroline, Metals and Alloys, General Chemistry, Reaction intermediate, 010402 general chemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, Bipyridine, chemistry, Computational chemistry, Pyridine, Atom, Materials Chemistry, Ceramics and Composites, Proton NMR, Benzophenone, [CHIM]Chemical Sciences
Abstract

International audience; The use of stoechiometric SmI 2 in combination with benzophenone and N-heterocyclic aromatics such as bipyridine, phenanthroline and neat pyridine allows the direct ortho-coupling of both partners in an atom economical reaction free of any other coupling additives. The transformation was investigated by 1 H NMR, X-ray studies and theoretical calculations providing reaction intermediates and the reaction mechanism.

Published
2020
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8. Effect of Cations on the Structure and Electrocatalytic Response of Polyoxometalate-Based Coordination Polymers

Author

Grégoire Paille, Marc Fontecave, Caroline Mellot-Draznieks, Grégory Nocton, Maria Gomez-Mingot, Pierre Mialane, William Salomon, Anne Dolbecq, Catherine Roch-Marchal, Jérôme Marrot, Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chaire Chimie des processus biologiques, Laboratoire de Chimie des Processus Biologiques (LCPB), Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie moléculaire (LCM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
chemistry.chemical_classification, 010405 organic chemistry, Coordination polymer, Stereochemistry, General Chemistry, Polymer, 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences, Crystallography, chemistry.chemical_compound, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Covalent bond, Polyoxometalate, General Materials Science, Counterion, Isostructural
Abstract

International audience; A series of six hybrid polymers based on the mixed-valent {ε-PMoV8MoVI4O40Zn4} (εZn) Keggin unit have been synthesized under hydrothermal conditions using tritopic (1,3,5-benzenetricarboxylate (trim) or 1,3,5-benzenetribenzoate (BTB)) or ditopic (4,4′-biphenyldicarboxylate (biphen)) linkers and [M(bpy)3]2+ (M = Co, Ru) complexes as charge-compensating cations. (TBA)2[Co(C10H8N2)3][PMo12O37(OH)3Zn4](C27H15O6)4/3·1.5C27H18O6·24H2O (Co-ε(BTB)4/3) has a three-dimensional (3D) framework with two interpenetrated networks and is isostructural to (TBA)4[PMo12O37(OH)3Zn4](C27H15O6)4/3·1.5C27H18O6·8H2O (ε(BTB)4/3). In Co-ε(BTB)4/3, two tetrabutylammonium (TBA+) cations over the four present in ε(BTB)4/3 are replaced by one [Co(bpy)3]2+ complex. [Co(C10H8N2)3][PMo12O37(OH)3Zn4](C9H3O6)Co(C10H8N2)4(H2O)·16H2O (Co-ε(trim) (bpy)2) is a 1D coordination polymer with two types of CoII-containing complexes, one covalently attached to the 1D chains and the other located in the voids as the counterion. [Ru(C10H8N2)3]4[PMo12O38(OH)2Zn4]2(C9H3O6)2·42H2O (Ru-ε2(trim)2) and [Ru(C10H8N2)3]3[PMo12O37(OH)3Zn4Cl]2(C14H8O4)2·24H2O (Ru-ε2(biphen)2) contain dimeric (εZn)2 units linked by dicarboxylate linkers, and both have [Ru(bpy)3]2+ countercations. Ru-ε2(trim)2 has a 3D framework, while Ru-ε2(biphen)2 is only 2D because of the presence of chloride ions on one-fourth of the ZnII ions. [P(C6H5)4]6[PMo12O37(OH)3Zn4]2(C9H3O6)2·18H2O (PPh4-ε2(trim)2) is isostructural to Ru-ε2(trim)2. These insoluble compounds entrapped in carbon-paste electrodes exhibit electrocatalytic activity for the hydrogen evolution reaction. The effects of their structure and the nature of the counterions on the activity have been studied. For the first time, different POM-based coordination polymers are compared for catalytic H2 production using controlled-potential electrolysis. This study shows that the nature of the countercation has a strong effect on the electrocatalytic activity of the compound.

Published
2017
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9. Divalent Thulium Crown Ether Complexes with Field-Induced Slow Magnetic Relaxation

Author

Grégory Nocton, Olivier Maury, Carole Duboc, Mathieu Xémard, Florian Molton, Olivier Cador, Boris Le Guennic, Marie Cordier, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Département de Chimie Moléculaire (DCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Laboratoire de Chimie - UMR5182 (LC), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon)-Institut de Chimie du CNRS (INC), CNRS, Ecole polytechnique, IR-RPE CNRS FR3443 network, École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
chemistry.chemical_classification, Lanthanide, Spintronics, 010405 organic chemistry, Ligand, chemistry.chemical_element, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, 3. Good health, 0104 chemical sciences, Coordination complex, law.invention, Inorganic Chemistry, Thulium, chemistry, Chemical physics, law, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, Ground state, Electron paramagnetic resonance, Crown ether
Abstract

International audience; The tailoring of the coordination chemistry around f-element centers is a crucial step for the development of compounds with slow magnetic relaxation, including single-molecule magnets (SMMs), which have great potential in molecular spintronics and for future quantum computing devices. Lanthanide ions are particularly interesting because the predominant electrostatic model of their bonding allows rationalizing their coordination symmetry. However, to the best of our knowledge, the redox properties of the lanthanides are not taken into account for the design of SMMs, and therefore all SMMs reported to date contain lanthanide ions in their trivalent oxidation state. In this Article, divalent lanthanide compounds presenting field-induced slow magnetic relaxation are reported. The rational design and synthesis of two TmII complexes with the 18-crown-6 ligand are presented along with their emission and EPR properties, which help to probe the desired nature of the ground state, that is, maximizing the anisotropy. The observed magnetic properties demonstrate their slow magnetic relaxation behavior in a moderate external magnetic field.

Published
2019
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10. Reversible electron transfer in organolanthanide chemistry

Author

Maxime Tricoire, Carine Clavaguéra, Arnaud Jaoul, Marie Cordier, Jules Moutet, Grégory Nocton, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire de Chimie-Physique (LCP), and Université de Cocody

Subjects
Lanthanide, 010405 organic chemistry, Ligand, Chemistry, Crystal structure, 010402 general chemistry, 01 natural sciences, Quantum chemistry, Redox, Article, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Electron transfer, quantum chemistry, Crystallography, Organolanthanide chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, lanthanides, electron density analysis, Isostructural, Palladium, Platinum
Abstract

International audience; This article relates the synthesis and characterization of novel heterobimetallic complexes containing a low-valent lanthanide, a tetradentate redox non-innocent ligand, viz. the 4,5,9,10-tetraazaphenanthrene, taphen ligand and transition metal fragments of PdMe 2 and PtMe 2. The experimental results are supported by a theoretical study. Investigation of their reduction properties allowed the formation of isostructural original heterotrimetallic complexes containing two Cp* 2 Yb fragments and the (taphen)MMe 2 (M = Pd and Pt) motifs. These complexes are stable in non-coordinating solvent such as toluene but decompose in coordinating solvents such as thf. Investigation of the internal electron transfer shows that the taphen ligand behaves as a two-electrons reservoir but is capable of transferring back only one electron in thf. This reversible electron(s) transfer is rare in organolanthanide chemistry and show the potential interest of these complexes in reductive chemistry. Additionally, the trinuclear complexes feature odd X-ray crystal structures in which a deviation of symmetry is observed. The latter observation was studied in depth using quantum chemistry calculations highlighting the role of non-covalent weak interactions.

Published
2019
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11. Lanthanidocenes: Synthesis, Structure, and Bonding of Linear Sandwich Complexes of Lanthanides

Author

Carine Clavaguéra, Marie Cordier, Grégory Nocton, Sébastien Zimmer, Mathieu Xémard, Violaine Goudy, Louis Ricard, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire de Chimie Physique D'Orsay (LCPO), and Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Lanthanide, 010405 organic chemistry, Ligand, Molecular orbital diagram, General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, Crystallography, chemistry.chemical_compound, Colloid and Surface Chemistry, Uranocene, chemistry, Ferrocene, Isostructural, [CHIM.OTHE]Chemical Sciences/Other, Isomerization, Conformational isomerism, ComputingMilieux_MISCELLANEOUS
Abstract

The Article presents the synthesis, structure, and bonding of a series of neutral and linear sandwich compounds with the cyclononatetraenyl (Cnt) ligand and divalent lanthanides. These compounds account for the emergence of the lanthanidocene series in reference to the ferrocene and uranocene. The synthetic strategy uses the solubility difference between two conformational isomers of the ligand, as well as the isomerization of the compounds induced by solvent coordination, yielding the isomorphous and isostructural neutral and rigorously linear sandwich complexes. The molecular structures feature a Cnt–Ln–Cnt angle of 180° and a ring size close to the Cnt–Cnt(centroid) distance. A qualitative molecular orbital diagram is provided, in D9d symmetry, and DFT calculations enforce the bonding model.

Published
2018

12. Phenylacetylene and Carbon Dioxide Activation by an Organometallic Samarium Complex

Author

Carlos Alvarez Lamsfus, Simon Karleskind, Violaine Goudy, Grégory Nocton, Mathieu Xémard, Laurent Maron, Marie Cordier, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
chemistry.chemical_classification, small molecule activation, 010405 organic chemistry, Chemical structure, Alkyne, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Small molecule, lcsh:QD146-197, 3. Good health, 0104 chemical sciences, Inorganic Chemistry, Samarium, chemistry.chemical_compound, Phenylacetylene, chemistry, Carbon dioxide, Polymer chemistry, lcsh:Inorganic chemistry, samarium complexes, C–H activation, C-H activation, [CHIM.OTHE]Chemical Sciences/Other
Abstract

Small molecule activation is a topic of growing importance and the use of low-valent f-elements to perform these reactions is nowadays well established. The complex Cptt2Sm(thf) (1, Cptt = 1,3-(tBu)2Cp) is shown to activate the alkyne C&ndash, H bond of phenylacetylene to form the Cptt2Sm(C&equiv, C&ndash, Ph)(thf) complex. The subsequent reaction of this Sm(III) complex with CO2 leads to the CO2 insertion, yielding a dimeric [Cptt2Sm(O2C&ndash, C&equiv, Ph)]2 complex (2), in which the carbon dioxide has been inserted in the Sm-C bond. Along with the experimental chemical structure analysis, theoretical calculations have been performed in order to rationalize the formation of 1 and 2.

Published
2018
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13. Synthesis and Reactivity of Low-Valent f-Element Iodide Complexes with Neutral Iminophosphorane Ligands

Author

Grégory Nocton, Audrey Auffrant, Karsten Meyer, Frank W. Heinemann, Louis Ricard, Thibault Cheisson, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Inorganic Chemistry, Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM) (ICMM), and Friedrich-Alexander Universität Erlangen-Nürnberg (FAU)

Subjects
Steric effects, Ytterbium, chemistry.chemical_classification, 010405 organic chemistry, Ligand, Iodide, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, 3. Good health, 0104 chemical sciences, Inorganic Chemistry, chemistry.chemical_compound, Ketyl, chemistry, Pyridine, Benzophenone, Reactivity (chemistry), Physical and Theoretical Chemistry, [CHIM.OTHE]Chemical Sciences/Other, ComputingMilieux_MISCELLANEOUS
Abstract

The coordination and reactivity of simple iodide salts of low-valent f elements [YbI2, SmI2, TmI2, and UI3(THF)4, where THF = tetrahydrofuran] with iminophosphorane (R3P═NR′) ligands are reported. The studied chelates were observed to adapt their geometry and effectively bind divalent ytterbium and samarium centers, as well as the trivalent uranium cation. The reactivity of the ytterbium adducts with benzophenone was found to be dependent on the steric demand of the supporting iminophosphorane ligand. In particular, a rare example of a stable charge-separated ketyl radical species is reported with ytterbium. Additionally, divalent thulium was observed to induce a reductive coupling at the ligand’s central pyridine ring.

Published
2018

14. Correction to Cerium Tetrakis(tropolonate) and Cerium Tetrakis(acethylacetonate) Are Not Diamagnetic but Temperature-Independent Paramagnets

Author

Corwin H. Booth, Grégory Nocton, Robert L. Halbach, Richard A. Andersen, and Laurent Maron

Subjects
010405 organic chemistry, Temperature independent, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Lewis structure, Inorganic Chemistry, Cerium, symbols.namesake, Crystallography, chemistry, symbols, Molecule, Diamagnetism, Singlet state, Physical and Theoretical Chemistry
Abstract

Author(s): Halbach, Robert L; Nocton, Gregory; Booth, Corwin H; Maron, Laurent; Andersen, Richard A | Abstract: Page 7295. In the Summary section of the article, the text should read "The energy of the closed-shell singlet that corresponds to the traditional Lewis structures used to represent these molecules is 400-700 cm-1 above the openshell triplet and singlet." instead of "The energy of the openshell singlet that corresponds to the traditional Lewis structures used to represent these molecules is 400-700 cm-1 above the open-shell triplet."

Published
2018

15. Cerium Tetrakis(tropolonate) and Cerium Tetrakis(acetylacetonate) Are Not Diamagnetic but Temperature-Independent Paramagnets

Author

Grégory Nocton, Corwin H. Booth, Richard A. Andersen, Robert L. Halbach, and Laurent Maron

Subjects
Magnetic moment, 010405 organic chemistry, Chemistry, chemistry.chemical_element, Crystal structure, Annulene, 010402 general chemistry, 01 natural sciences, Magnetic susceptibility, 0104 chemical sciences, Inorganic Chemistry, Paramagnetism, Cerium, Crystallography, Dodecahedron, Diamagnetism, Physical and Theoretical Chemistry
Abstract

A new synthesis of cerium tetrakis(tropolonate), Ce(trop)4, where trop is deprotonated 2-hydroxy-2,4,6-cycloheptatrienone) or Ce(O2C7H5)4, is developed that results in dark-purple crystals whose X-ray crystal structure shows that the geometry of the eight-coordinate compound closely resembles a D2 d dodecahedron, based on shape parameters. The magnetic susceptibility as a function of the temperature (4-300 K) shows that it is a temperature-independent paramagnet, χ = 1.2(3) × 10-4 emu/mol, and the LIII-edge X-ray absorption near-edge structure spectrum shows that the molecule is multiconfigurational, comprised of a f1:f0 configuration mixture in a 50:50 ratio. Ce(acac)4 and Ce(tmtaa)2 (where acac is acetylacetonate and tmtaaH2 is tetramethyldibenzotetraaza[14]annulene) have similar physical properties, as does the solid-state compound CeO2. The concept is advanced that trop-, acac-, tmtaa2-, cot2-, and O2- are redox-active ligands that function as electron donors, rendering the classification of these compounds according to their oxidation numbers misleading because their magnetic susceptibilities, χ, are positive and their effective magnetic moments, μeff, lie in the range of 0.1-0.7 μB at 300 K.

Published
2018

16. Assessment of Density Functionals for Computing Thermodynamic Properties of Lanthanide Complexes

Author

Carine Clavaguéra, Arnaud Jaoul, Grégory Nocton, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and ANR-15-CE29-0019,ReDivaLan,Transfert électronique dans les organolanthanides : une approche spectroscopique et théorique(2015)

Subjects
Lanthanide, 010304 chemical physics, Ligand, Phenanthroline, Thermodynamics, Electronic structure, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, electron transfer, electronic structure, 01 natural sciences, Quantum chemistry, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, chemistry.chemical_compound, Electron transfer, chemistry, Atomic orbital, Computational chemistry, 0103 physical sciences, density functional calculations, Density functional theory, lanthanides, Physical and Theoretical Chemistry, ELF (electron localization function)
Abstract

International audience; The equilibrium between the radical phenanthroline complex Cp*2 Sm(phen) and the coupling product (Cp*2 Sm(phen))2 has been investigated based on quantum chemistry calculations. Topological analyses pointed out that the C-C bond created has a partial covalent character, explaining why both the monomeric and the dimeric forms exist in equilibrium. A large variety of density functionals have been tested to reproduce experimental thermodynamic data for this equilibrium. Finally, the PBE0-D3 and M06-2X functionals lead to a good evaluation of the energies and enable a correct description of the ligand to metal charge transfer, both in the 4f and 5d metal orbitals.

Published
2017
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17. Tuning the Stability of Pd(IV) Intermediates Using a Redox Non-innocent Ligand Combined with an Organolanthanide Fragment

Author

Violaine Goudy, Arnaud Jaoul, Carine Clavaguéra, Grégory Nocton, Marie Cordier, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and ANR-15-CE29-0019,ReDivaLan,Transfert électronique dans les organolanthanides : une approche spectroscopique et théorique(2015)

Subjects
chemistry.chemical_classification, 010405 organic chemistry, Stereochemistry, Ligand, Communication, chemistry.chemical_element, General Chemistry, Electronic structure, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, Photochemistry, 01 natural sciences, Biochemistry, Redox, Oxidative addition, Catalysis, Non-innocent ligand, 3. Good health, 0104 chemical sciences, Divalent, Colloid and Surface Chemistry, chemistry, Moiety, Palladium
Abstract

International audience; The unique combination of a divalent organolanthanide fragment, Cp*2Yb, with bipyrimidine (bipym) and a palladium bis-alkyl fragment, PdMe2, allows the rapid formation and stabilization of a PdIV tris-alkyl moiety after oxidative addition with MeI. The crucial role of the organolanthanide fragment is demonstrated by the substitution of bipym by the 4,5,9,10-tetraazaphenanthrene ligand, which drastically modifies the electronic structure and tunes the stability of the PdIV species.

Published
2017
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18. Electronic Structures of Mono-Oxidized Copper and Nickel Phosphasalen Complexes

Author

Irene Mustieles Marín, Thibault Cheisson, Rohit Singh-Chauhan, Grégory Nocton, Audrey Auffrant, Marie Cordier, Christian Herrero, Carine Clavaguéra, Université Paris-Saclay, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ANR-13-JS07-0001,PsalenOx,Oxydation de complexes à ligand phosphasalen(2013), and École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Substituent, chemistry.chemical_element, Electronic structure, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Catalysis, law.invention, Metal, chemistry.chemical_compound, nickel, Oxidation state, law, Electron paramagnetic resonance, 010405 organic chemistry, Ligand, Organic Chemistry, non-innocent ligands, General Chemistry, electronic structure, Non-innocent ligand, 0104 chemical sciences, Nickel, Crystallography, chemistry, visual_art, copper, visual_art.visual_art_medium, phosphasalen
Abstract

International audience; Non‐innocent ligands render the determination of the electronic structure in metal complexes difficult. As such, a combination of experimental techniques and quantum chemistry are required to correctly elucidate them. This paper deals with the one‐electron oxidation of copper(II) and nickel(II) complexes featuring a phosphasalen ligand (Psalen), which differs from salen analogues by the presence of iminophosphorane groups (P=N) instead of imines. Various experimental techniques (X‐ray diffraction, cyclic voltammetry, NMR, EPR, and UV/Vis spectroscopies, and magnetic measurements) as well as quantum chemical calculations were used to define the electronic structure of the oxidized complexes. These can be modified by a small change in the ligand structure, that is, the replacement of a tert‐butyl group by a methoxy on the phenoxide ring. The different techniques have allowed quantifying the amount of spin density located on the metal center and on the Psalen ligands. All complexes were found to possess a multi‐configurational ground state, in which the ratio of the +II versus +III oxidation state of the metal center, and therefore the phenolate versus phenoxyl radical ligand character, varies upon the substituents. The tert‐butyl group favors a strong localization on the metal center whereas with the methoxy group the metallic configurations decrease and the ligand configurations increase. The importance of the geometrical considerations compared with the electronic substituent effect is highlighted by the differences observed between the solid‐state (EPR, magnetic measurements) and solution characterizations (EPR and NMR data).

Published
2017
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19. A Tetracoordinated Phosphasalen Nickel(III) Complex

Author

Xavier F. Le Goff, Louis Ricard, Thi-Phuong-Anh Cao, Audrey Auffrant, Grégory Nocton, Laboratoire Hétéroéléments et Coordination (DCPH), and École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Diffraction, Inorganic chemistry, Imine, Salt (chemistry), chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Catalysis, law.invention, Metal, chemistry.chemical_compound, law, Spectroscopy, Electron paramagnetic resonance, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, 010405 organic chemistry, Ligand, General Medicine, General Chemistry, 0104 chemical sciences, Crystallography, Nickel, chemistry, visual_art, visual_art.visual_art_medium, [CHIM.OTHE]Chemical Sciences/Other
Abstract

The oxidation of a Ni(II) complex bearing a tetradentate phosphasalen ligand, which differs from salen by the presence of an iminophosphorane (PN) in place of an imine unit, was easily achieved by addition of a silver salt. The site of this oxidation was investigated with a combination of techniques (NMR, EPR, UV/Vis spectroscopy, X-ray diffraction, magnetic measurements) as well as DFT calculations. All data are in agreement with a high-valent Ni(III) center concentrating the spin density. This markedly differs from precedents in the salen series for which oxidation on the metal was only observed at low temperature or in the presence of additional ligands or anions. Therefore, thanks to the good electron-donating properties of the phosphasalen ligand, [Ni(Psalen)](+) represents a rare example of a tetracoordinated high-valent nickel complex in presence of a phenoxide ligand.

Published
2013
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20. Influence of the Torsion Angle in 3,3′-Dimethyl-2,2′-bipyridine on the Intermediate Valence of Yb in (C5Me5)2Yb(3,3′-Me2-bipy)

Author

Grégory Nocton, Richard A. Andersen, Laurent Maron, Corwin H. Booth, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire Hétéroéléments et Coordination (DCPH), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Valence (chemistry), 010405 organic chemistry, Chemistry, Organic Chemistry, Crystal structure, Dihedral angle, 010402 general chemistry, 01 natural sciences, 2,2'-Bipyridine, 0104 chemical sciences, Inorganic Chemistry, Bipyridine, chemistry.chemical_compound, Crystallography, Computational chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Singlet state, Physical and Theoretical Chemistry, Triplet state, Ground state
Abstract

International audience; The synthesis and X-ray crystal structures of Cp*2Yb(3,3′-Me2bipy) and [Cp*2Yb(3,3′-Me2bipy)][Cp*2YbCl1.6I0.4]*CH2Cl2 are described. In both complexes, the NCCN torsion angles are approximately 40°. The temperature-independent value of nf of 0.17 shows that the valence of ytterbium in the neutral adduct is multiconfigurational, in reasonable agreement with a CASSCF calculation that yields a nf value of 0.27; that is, the two configurations in the wave function are f13(π*1)1 and f14(π*1)0 in a ratio of 0.27:0.73, respectively, and the open-shell singlet lies 0.28 eV below the triplet state (nf accounts for f-hole occupancy; that is, nf = 1 when the configuration is f13 and nf = 0 when the configuration is f14). A correlation is outlined between the value of nf and the individual ytterbocene and bipyridine fragments such that, as the reduction potentials of the ytterbocene cation and the free x,x′-R2-bipy ligands approach each other, the value of nf and therefore the f13:f14 ratio reaches a maximum; conversely, the ratio is minimized as the disparity increases.

Published
2013
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21. Synthesis and Characterization of 1,1′-Diphosphaplumbocenes: Oxidative Ligand Transfer Reactions with Divalent Thulium Complexes

Author

Aurélien Momin, Louis Ricard, Agathe Martinez, Grégory Nocton, Dominique Harakat, Xavier F. Le Goff, Florian Jaroschik, Institut de Chimie Moléculaire de Reims - UMR 7312 (ICMR), SFR Condorcet, Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-SFR CAP Santé (Champagne-Ardenne Picardie Santé), Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Université de Reims Champagne-Ardenne (URCA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie moléculaire (LCM), and École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Lanthanide, chemistry.chemical_classification, 010405 organic chemistry, Chemistry, Ligand, Stereochemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Organic Chemistry, chemistry.chemical_element, Nuclear magnetic resonance spectroscopy, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Divalent, Inorganic Chemistry, NMR spectra database, Crystallography, Thulium, Cyclopentadienyl complex, Proton NMR, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry
Abstract

International audience; The new 1,1′-diphosphaplumbocenes Pb(Dtp)2(Dtp = 2,5-di-tert-butyl-3,4-dimethylphospholyl) and Pb(Dsp)2(Dsp = 2,5-ditrimethylsilyl-3,4-dimethylphospholyl) have beensynthesized and characterized by multinuclear NMR spectroscopy.207Pb NMR spectra of both complexes, as well as for theknown complex Pb(Htp)2 (Htp = 2,5-di-tert-butylphospholyl),show that the phospholyl ligands lead to an important downfieldshift compared with that of cyclopentadienyl based plumbocenes.X-ray diffraction studies of the Pb(Dtp)2 complex revealed astructure with two slightly bent η5-bound ligands. This complexwas employed in the oxidative ligand transfer reaction with bulkydivalent thulium complexes. In the case of Tm(Dtp)2, the firstexample of a monomeric trivalent tris(phospholyl)lanthanidecomplex Tm(Dtp)3 was obtained. X-ray diffraction studies andlow-temperature 1H NMR studies show the η1 coordination mode of the third Dtp ligand. In contrast, oxidation of Tm(Cpttt)2(Cpttt is for tris-tert-butylcyclopentadienyl) led presumably to the formation of the ion pair complex [Tm(Cpttt)2][Dtp], in whichno interaction between the free Dtp ligand and Tm was observed, as shown by variable temperature 1H and 31P NMR studies.The new trivalent complexes could be reduced back to the original divalent complexes with potassium graphite.

Published
2016
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22. Self-Assembly of Polyoxo Clusters and Extended Frameworks by Controlled Hydrolysis of Low-Valent Uranium

Author

Fabien Burdet, Grégory Nocton, Marinella Mazzanti, Jacques Pécaut, Reconnaissance Ionique et Chimie de Coordination (RICC), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-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)-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)-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)-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), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Web of science, Chemistry, 010405 organic chemistry, Inorganic chemistry, chemistry.chemical_element, General Chemistry, Actinide, General Medicine, Uranium, 010402 general chemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Hydrolysis, [CHIM]Chemical Sciences, Self-assembly, ComputingMilieux_MISCELLANEOUS
Abstract

Reference EPFL-ARTICLE-203035doi:10.1002/anie.200702374View record in Web of Science Record created on 2014-11-07, modified on 2016-08-10

Published
2007
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23. Reversible C-C coupling in phenanthroline complexes of divalent samarium and thulium

Author

Louis Ricard, Grégory Nocton, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), and Tard, Cédric

Subjects
Phenanthroline, chemistry.chemical_element, 010402 general chemistry, Photochemistry, 01 natural sciences, Catalysis, Divalent, Adduct, C c coupling, chemistry.chemical_compound, Materials Chemistry, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, 010405 organic chemistry, Ligand, Metals and Alloys, General Chemistry, 3. Good health, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Samarium, Crystallography, Thulium, chemistry, [CHIM.OTHE] Chemical Sciences/Other, Yield (chemistry), Ceramics and Composites, [CHIM.OTHE]Chemical Sciences/Other
Abstract

The reaction of a series of organolanthanide fragments of samarium and thulium with phenanthroline is reported. All adducts couple in the 4-position of the phenanthroline ligand to yield the 4–4′ dimers when they crystallize. The analysis of the solution structure revealed a thermally reversible C–C coupling in all cases.

Published
2015

24. Reversible Sigma C-C Bond Formation Between Phenanthroline Ligands Activated by (C5Me5)2Yb

Author

Wayne W. Lukens, Corwin H. Booth, Richard A. Andersen, Sergio S. Rozenel, Grégory Nocton, Scott Medling, Laurent Maron, Laboratoire de chimie moléculaire (LCM), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry, Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010405 organic chemistry, Chemistry, Phenanthroline, Inorganic chemistry, General Chemistry, Electronic structure, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, 3. Good health, Adduct, Crystallography, Bipyridine, chemistry.chemical_compound, Colloid and Surface Chemistry, Atomic orbital, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Ground state, HOMO/LUMO, Diimine
Abstract

International audience; The electronic structure and associated magnetic properties of the 1,10-phenanthroline adducts of Cp* 2 Yb are dramatically different from those of the 2,2'-bipyridine adducts. The monomeric phenanthroline adducts are ground state triplets that are based upon trivalent Yb(III), f 13 and (phen·-) that are only weakly exchange coupled, which is in contrast to the bipyridine adducts whose ground states are multiconfigurational, open-shell singlets in which ytterbium is intermediate valent (J. Am. Chem. Soc, 2009, 131, 6480; J. Am. Chem. Soc, 2010, 132, 17537). The origin of these different physical properties is traced to the number and symmetry of the LUMO and LUMO + 1 of the heterocyclic amine ligands. The bipy·-has only one π* 1 orbital of b 1 symmetry of accessible energy but phen·-has two π* orbitals of b 1 and a 2 symmetry that are energetically accessible. The carbon pπ-orbitals have different nodal properties and coefficients and their energies and therefore populations change depending on the position and number of methyl substitutions on the ring. A chemical ramification of the change in electronic structure is that Cp* 2 Yb(phen) is a dimer, when crystallized from toluene solution, but a monomer when sublimed at 180-190 °C. When 3,8-Me 2 phenanthroline is used, the adduct Cp* 2 Yb(3,8-Me 2 phen) exist in the solution in a dimer-monomer equilibrium in which ΔG is near zero. The adducts with 3-Me, 4-Me, 5-Me, 3,8-Me 2 and 5,6-Me 2-phenanthroline are isolated and characterized by solid state X-ray crystallography, magnetic susceptibility and L III-edge XANES spectroscopy as a function of temperature and variable temperature 1 H NMR spectroscopy.

Published
2014
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25. Multiple One-Electron Transfers in Bipyridine Complexes of Bis(phospholyl) Thulium

Author

Léa Jacquot, Grégory Nocton, Mathieu Xémard, Carine Clavaguéra, Tard, Cédric, Laboratoire de chimie moléculaire (LCM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
010405 organic chemistry, Ligand, Organic Chemistry, chemistry.chemical_element, Electron, 010402 general chemistry, Photochemistry, 01 natural sciences, Redox, Divalent metal, 0104 chemical sciences, Ion, Inorganic Chemistry, Bipyridine, chemistry.chemical_compound, Electron transfer, Crystallography, Thulium, chemistry, [CHIM.OTHE] Chemical Sciences/Other, Physical and Theoretical Chemistry, [CHIM.OTHE]Chemical Sciences/Other, ComputingMilieux_MISCELLANEOUS
Abstract

The synthesis of original neutral bis(phospholyl) thulium complexes, Dtp2Tm(L), where L is tetramethylbiphosphinine (tmbp) and bipyridine (bipy), is reported. The electronic structures of these complexes have been investigated and it appears that, in both cases, an electron transfer occurs from the divalent metal to the ligand, a consequence of the strong reduction potential of the bis(phospholyl) thulium fragment, Dtp2Tm. When 1 equiv of bipyridine is added to the Dtp2Tm(tmbp) complex, another electron transfer occurs to form the Dtp2Tm(bipy) complex along with free tmbp ligand. Astonishingly, despite the apparent trivalent nature of the thulium center, the Dtp2Tm(bipy) complex is still reactive toward neutral bipyridine to form a new complex in which one phospholyl ligand is replaced by a bipyridine radical anion. An experimental kinetic analysis is reported to rationalize this unprecedented redox reaction with thulium and reveals an associative type of mechanism.

Published
2014

26. Thermal Dihydrogen Elimination from Cp☆2Yb(4,5-diazafluorene)

Author

Laurent Maron, Richard A. Andersen, Grégory Nocton, Corwin H. Booth, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Magnetic moment, 010405 organic chemistry, Chemistry, Organic Chemistry, 010402 general chemistry, 01 natural sciences, XANES, 0104 chemical sciences, Adduct, Inorganic Chemistry, Computational chemistry, Atom, Physical chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Complete active space, Physical and Theoretical Chemistry, Triplet state, Spectroscopy, Bimetallic strip
Abstract

International audience; The reaction of 4,5-diazafluorene with Cp*2Yb(OEt2), where Cp* is pentamethylcyclopentadienyl, affords the isolable adduct Cp*2Yb(4,5-diazafluorene) (1), which slowly eliminates H2 to form Cp*2Yb(4,5-diazafluorenyl) (2); the net reaction is therefore 1 → 2 + H*. The ytterbium atom in 1 is shown to be intermediate valent by variable-temperature LIII-edge X-ray absorption near-edge (XANES) spectroscopy, consistent with its low effective magnetic moment (μeff). The experimental studies are supported by complete active space self-consistent field (CASSCF) calculations, showing that two open-shell singlets lie below the triplet state. The two open-shell singlets are calculated to be multiconfigurational and closely spaced, in agreement with the observed temperature dependence of the XANES and χ data, which are fit to a Boltzmann distribution. A mechanism for dihydrogen formation is proposed on the basis of kinetic and labeling studies to involve the bimetallic complex (Cp*2Yb)2(4,5-diazafluorenyl)2, in which the heterocyclic amine ligands are joined by a carbon-carbon bond at C(9)-C(9′).

Published
2013
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27. CO Activation by (Diphosphane)platinum(0): Carbonate and Acetone Formation - Experimental and Mechanistic Study

Author

Emmanuel Nicolas, Nicolas Mézailles, Grégory Nocton, Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Laboratoire Hétéroéléments et Coordination (DCPH), and École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Dimer, Iodide, chemistry.chemical_element, Carbonylation, Crystal structure, 010402 general chemistry, Photochemistry, 01 natural sciences, Medicinal chemistry, Mechanistic studies, Inorganic Chemistry, chemistry.chemical_compound, Diphosphane, Reactivity (chemistry), [CHIM.COOR]Chemical Sciences/Coordination chemistry, Carbon monoxide, Platinum, chemistry.chemical_classification, 010405 organic chemistry, Reactivity, Small molecule activation, 0104 chemical sciences, 3. Good health, Density functional calculations, chemistry, Methyl group
Abstract

International audience; The platinum(II) complex [(dcpp)Pt(C7H7)H] (1) [dcpp = 1,3-bis(dicyclohexylphosphanyl)propane] reacts under 1 atm of CO to form the bis(carbonyl) complex of Pt0, [(dcpp)Pt(CO)2] (2). Complex 2 slowly crystallizes in toluene solution to form crystals of the Pt0 dimer [(dcpp)(η1-CO)Pt{μ-C(O)}Pt(dcpp)] (3) in which one Pt atom is only three-coordinated with the diphosphane dcpp and one μ-C(O), while the other is coordinated in a tetrahedral arrangement with one μ-C(O) and one η1-CO. Complexes 2 and 3 were characterized in solution by 31P NMR spectroscopy, and complex 3 readily reacts with O2 to form the carbonate complex, [(dcpp)Pt(CO3)] (4). The reaction of the dimeric complex 3 with MeI allows the insertion of a methyl group into the carbonyl group to form the PtII complex [(dcpp)Pt(C(O)Me)I] (5). Reaction of another equivalent of MeI with complex 5 leads to the formation and elimination of acetone and the bis(iodide) complex [(dcpp)PtI2] (6). X-ray crystal structures of complexes 3 and 4 are reported along with DFT calculations and mechanistic studies of the formation of 3, 4, 5, and 6.

Published
2013
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28. Diniobium Inverted Sandwich Complexes with µ-η6:η6-Arene Ligands: Synthesis, Kinetics of Formation, and Electronic Structure

Author

A. L. David Kilcoyne, Stosh A. Kozimor, Thomas L. Gianetti, Stefan G. Minasian, Tolek Tyliszczak, John Arnold, Grégory Nocton, David K. Shuh, Neil C. Tomson, Robert G. Bergman, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire Hétéroéléments et Coordination (DCPH), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chemistry Division, Los Alamos National Laboratory, Los Alamos National Laboratory (LANL), Advanced Light Source [LBNL Berkeley] (ALS), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)

Subjects
010405 organic chemistry, Chemistry, Stereochemistry, Kinetics, Cationic polymerization, Protonation, General Chemistry, Electronic structure, 010402 general chemistry, 01 natural sciences, Biochemistry, Small molecule, Catalysis, XANES, 0104 chemical sciences, Crystallography, Colloid and Surface Chemistry, Reactivity (chemistry), [CHIM.COOR]Chemical Sciences/Coordination chemistry, Absorption (chemistry)
Abstract

Monometallic niobium arene complexes [Nb(BDI)(N(t)Bu)(R-C(6)H(5))] (2a: R = H and 2b: R = Me, BDI = N,N'-diisopropylbenzene-β-diketiminate) were synthesized and found to undergo slow conversion into the diniobium inverted arene sandwich complexes [[(BDI)Nb(N(t)Bu)](2)(μ-RC(6)H(5))] (7a: R = H and 7b: R = Me) in solution. The kinetics of this reaction were followed by (1)H NMR spectroscopy and are in agreement with a dissociative mechanism. Compounds 7a-b showed a lack of reactivity toward small molecules, even at elevated temperatures, which is unusual in the chemistry of inverted sandwich complexes. However, protonation of the BDI ligands occurred readily on treatment with [H(OEt(2))][B(C(6)F(5))(4)], resulting in the monoprotonated cationic inverted sandwich complex 8 [[(BDI(#))Nb(N(t)Bu)][(BDI)Nb(N(t)Bu)](μ-C(6)H(5))][B(C(6)F(5))(4)] and the dicationic complex 9 [[(BDI(#))Nb(N(t)Bu)](2)(μ-RC(6)H(5))][B(C(6)F(5))(4)](2) (BDI(#) = (ArNC(Me))(2)CH(2)). NMR, UV-vis, and X-ray absorption near-edge structure (XANES) spectroscopies were used to characterize this unique series of diamagnetic molecules as a means of determining how best to describe the Nb-arene interactions. The X-ray crystal structures, UV-vis spectra, arene (1)H NMR chemical shifts, and large J(CH) coupling constants provide evidence for donation of electron density from the Nb d-orbitals into the antibonding π system of the arene ligands. However, Nb L(3,2)-edge XANES spectra and the lack of sp(3) hybridization of the arene carbons indicate that the Nb → arene donation is not accompanied by an increase in Nb formal oxidation state and suggests that 4d(2) electronic configurations are appropriate to describe the Nb atoms in all four complexes.

Published
2013
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29. Synthesis, Structure and Bonding of Stable Complexes of Pentavalent Uranyl

Author

Pascale Maldivi, Lionel Dubois, Paweł Horeglad, Jacques Pécaut, Norman M. Edelstein, Marinella Mazzanti, Valentina Vetere, Grégory Nocton, 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), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Maldivi, Pascale, 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), and 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)

Subjects
actinide chemistry, Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, DFT, Catalysis, law.invention, chemistry.chemical_compound, Colloid and Surface Chemistry, law, Pyridine, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Electron paramagnetic resonance, Crown ether, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, uranyle, Schiff base, 010405 organic chemistry, Ligand, Chemistry, General Chemistry, [CHIM.COOR] Chemical Sciences/Coordination chemistry, Uranyl, Magnetic susceptibility, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Crystallography, [CHIM.THEO] Chemical Sciences/Theoretical and/or physical chemistry, Cyclic voltammetry
Abstract

Stable complexes of pentavalent uranyl [UO(2)(salan-(t)Bu(2))(py)K](n) (3), [UO(2)(salan-(t)Bu(2))(py)K(18C6)] (4), and [UO(2)(salophen-(t)Bu(2))(thf)]K(thf)(2)}(n) (8) have been synthesized from the reaction of the complex {[UO(2)py(5)][KI(2)py(2)]}(n) (1) with the bulky amine-phenolate ligand potassium salt K(2)(salan-(t)Bu(2)) or the Schiff base ligand potassium salt K(2)(salophen-(t)Bu(2)) in pyridine. They were characterized by NMR, IR, elemental analysis, single crystal X-ray diffraction, UV-vis spectroscopy, cyclic voltammetry, low-temperature EPR, and variable-temperature magnetic susceptibility. X-ray diffraction shows that 3 and 8 are polymeric and 4 is monomeric. Crystals of the monomeric complex [U(V)O(2)(salan-(t)Bu(2))(py)][Cp*(2)Co], 6, were also isolated from the reduction of [U(VI)O(2)(salan-(t)Bu(2))(py)], 5, with Cp*(2)Co. Addition of crown ether to 1 afforded the highly soluble pyridine stable species [UO(2)py(5)]I.py (2). The measured redox potentials E(1/2) (U(VI)/U(V)) are significantly different for 2 (-0.91 and -0.46 V) in comparison with 3, 4, 5, 7 and 9 (in the range -1.65 to -1.82 V). Temperature-dependent magnetic susceptibility data are reported for 4 and 7 and give mu(eff) of 2.20 and 2.23 mu(B) at 300 K respectively, which is compared with a mu(eff) of 2.6(1) mu(B) (300 K) for 2. Complexes 1 and 2 are EPR silent (4 K) while a rhombic EPR signal (g(x) = 1.98; g(y) = 1.25; g(z) = 0.74 (at 4 K) was measured for 4. The magnetic and the EPR data can be qualitatively analyzed with a simple crystal field model where the f electron has a nonbonding character. However, the temperature dependence of the magnetic susceptibility data suggests that one or more excited states are relatively low-lying. DFT studies show unambiguously the presence of a significant covalent contribution to the metal-ligand interaction in these complexes leading to a significant lowering of the pi(u)*. The presence of a back-bonding interaction is likely to play a role in the observed solution stability of the [UO(2)(salan-(t)Bu(2))(py)K] and [UO(2)(salophen-(t)Bu(2))(py)K] complexes with respect to disproportionation and hydrolysis.

Published
2009

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