Hammarback, L. Anders, Eastwood, Jonathan B., Burden, Thomas J. et al. (6 more authors) (2022) A comprehensive understanding of carbon-carbon bond formation by alkyne migratory insertion into manganacycles. Chemical Science. ISSN 2041-6539
Abstract
Migratory insertion (MI) is one of the most important processes underpinning the transition metal-catalysed formation of C-C and C-X bonds. In this work, a comprehensive model of MI is presented, based on the direct observation of the states involved in the coupling of alkynes with cyclometallated ligands, augmented with insight from computational chemistry. Time-resolved spectroscopy demonstrates that photolysis of complexes [Mn(C^N)(CO)4] (C^N = cyclometalated ligand) results in ultra-fast dissociation of a CO ligand. Performing the experiment in a toluene solution of an alkyne results in the initial formation of a solvent complex fac-[Mn(C^N)(toluene)(CO)3]. Solvent substitution gives an η2-alkyne complex fac-[Mn(C^N)(η2-R1C2R2)(CO)3] which undergoes MI of the unsaturated ligand into the Mn-C bond. These data allowed for the dependence of second order rate constants for solvent substitution and first order rate constants for C-C bond formation to be determined. A systematic investigation into the influence of the alkyne and C^N ligand on this process is reported. The experimental data enabled the development of a computational model for the MI reaction which demonstrated that a synergic interaction between the metal and the nascent C-C bond controls both the rate and regiochemical outcome of the reaction. The time-resolved spectroscopic method enabled the observation of a multi-step reaction occurring over 8 orders of magnitude in time, including the formation of solvent complexes, ligand substitution and two sequential C-C bond formation steps.
Metadata
Item Type: | Article | ||||
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Copyright, Publisher and Additional Information: | © 2022 The Royal Society of Chemistry. | ||||
Dates: |
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Institution: | The University of York | ||||
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) | ||||
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Depositing User: | Pure (York) | ||||
Date Deposited: | 30 Aug 2022 14:50 | ||||
Last Modified: | 13 Mar 2024 00:21 | ||||
Published Version: | https://doi.org/10.1039/d2sc02562k | ||||
Status: | Published online | ||||
Refereed: | Yes | ||||
Identification Number: | https://doi.org/10.1039/d2sc02562k | ||||
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