Christopher Gordon

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Gordon

First Name

Christopher

ORCID

0000-0002-2199-8995

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Publications 1 - 10 of 34

Chemical Shift Tensors - Why Should We Care?
Gordon, Christopher; Copéret, Christophe (2019)
Chimia
π-Bond Character in Metal-Alkyl Compounds for C-H Activation: How, When, and Why?
Gordon, Christopher; Culver, Damien B.; Conley, Matthew P.; et al. (2019)
Journal of the American Chemical Society
Promoting Terminal Olefin Metathesis with a Supported Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Catalyst
Pucino, Margherita; Inoue, Mariko; Gordon, Christopher; et al. (2018)
Angewandte Chemie. International Edition
W-183 NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
Hillenbrand, Julius; Leutzsch, Markus; Gordon, Christopher; et al. (2020)
Angewandte Chemie. International Edition
Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. 1H,183W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable 5J‐coupling between the 183W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity to an extent that the tungstenacyclobutadiene formed in the initial [2+2] cycloaddition step is over‐stabilized and the catalytic turnover brought to a halt. Guided by the 183W NMR shifts as a proxy for the Lewis acidity of the central atom and by an accompanying chemical shift tensor analysis of the alkylidyne unit, the ligand design was revisited and a more strongly π‐donating all‐alkoxide ligand prepared. The new expanded chelate complex has a tempered Lewis acidity and outperforms the classical Schrock catalyst, carrying monodentate tert‐butoxy ligands, in terms of rate and functional‐group compatibility.
Understanding ¹²⁵Te NMR chemical shifts in disymmetric organo-telluride compounds from natural chemical shift analysis
Pietrasiak, Ewa; Gordon, Christopher; Copéret, Christophe; et al. (2020)
Physical Chemistry Chemical Physics
Organotellurium compounds of general formula X–Te–R display a broad range of chemical shifts that are very sensitive to the X and R substituents. In order to link the 125Te chemical shift of a series of perfluoroalkyl aryl tellurides to their electronic structure, the chemical shielding tensors of the 125Te nuclei were calculated by density functional theory (DFT) and further analyzed by a decomposition into contributions of natural localized molecular orbitals (NLMOs). The analysis indicated that the variation in 125Te chemical shifts in molecules 1–13 is mainly due to the magnetic coupling of the tellurium p-character lone pair with antibonding orbitals perpendicular to it {σ*(Te–X) and σ*(Te–C(Ar))} upon action of an external magnetic field. The strength of the coupling is affected by electronic properties of the X-substituents, polarization of the antibonding orbitals and presence of secondary interactions perturbing the energy of these orbitals. The lower in energy and the more polarized towards tellurium the antibonding orbitals are, the stronger is the coupling and the more deshielded the tellurium nucleus.
Silica‐Grafted Tris(neopentyl)aluminum: A Monomeric Aluminum Solid Co‐catalyst for Efficient Nickel‐Catalyzed Ethene Dimerization
Moroz, Ilia B.; Florian, Pierre; Viger-Gravel, Jasmine; et al. (2020)
Angewandte Chemie. International Edition
A silica‐supported monomeric alkylaluminum co‐catalyst was prepared via surface organometallic chemistry by contacting tris(neopentyl)aluminum and partially dehydroxylated silica. This system, fully characterized by solid‐state 27Al NMR spectroscopy augmented by computational studies, efficiently activates (nBu3P)2NiCl2 towards dimerization of ethene, demonstrating comparable activity to previously reported dimeric diethylaluminum chloride supported on silica. Three types of aluminum surface species have been identified: monografted tetracoordinated Al species as well as two types of bisgrafted Al species—tetra‐ and pentacoordinated. Of them, only the monografted Al species is proposed to be able to activate the (n Bu3P)2NiCl2 complex and generate the active cationic species. © 2020 Wiley-VCH Verlag GmbH & Co.
C-H Activation and Olefin Insertion in d8 and d0 Complexes: Same Elementary Steps, Different Electronics
Bumberger, Andreas E.; Gordon, Christopher; Trummer, David; et al. (2020)
Helvetica Chimica Acta
Low-Coordinated Titanium(III) Alkyl-Molecular and Surface-Complexes: Detailed Structure from Advanced EPR Spectroscopy
Allouche, Florian; Klose, Daniel; Gordon, Christopher; et al. (2018)
Angewandte Chemie. International Edition
Alkyne gem‐Hydrogenation: Formation of Pianostool Ruthenium Carbene Complexes and Analysis of Their Chemical Character
Biberger, Tobias; Gordon, Christopher; Leutzsch, Markus; et al. (2019)
Angewandte Chemie. International Edition
Probing the Electronic Structure of Spectator Oxo Ligands by 17O NMR Spectroscopy
Gordon, Christopher; Copéret, Christophe (2020)
Chimia
Spectator oxo ligands are ubiquitous in catalysis, in particular in olefin epoxidation and olefin metathesis. Here we use computationally derived 17O NMR parameters to probe the electronic structure of spectator oxo ligands in these two reactions. We show that 17O NMR parameters allow to distinguish between doubly-bonded and triply-bonded oxo ligands, giving detailed insights into the frontier molecular orbitals involved in the metaloxo bonds along the reaction pathway. On the one hand, our study shows that in olefin epoxidation catalysed by methyltrioxorhenium (MTO), the oxo ligand significantly changes its bonding mode upon formation of the oxygen-transferring Re-oxo-bisperoxo-species, changing its nature from a doubly bonded to a triply bonded oxo ligand. On the other hand, only minor changes in the binding mode are found along the olefin metathesis reaction pathway with Mo- and W-based oxo-alkylidene species, in which the oxo ligand behaves as a triply bonded ligand throughout the reaction. This finding contrasts earlier studies that proposed that the change of binding mode of the oxo ligand was key to metallacyclobutane formation.

Publications 1 - 10 of 34

Christopher Gordon

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