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Direct Observation of the Dynamics of Ylide Solvation by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy
[Image: see text] The photoexcitation of α-diazocarbonyl compounds produces singlet carbene intermediates that react with nucleophilic solvent molecules to form ylides. The zwitterionic nature of these newly formed ylides induces rapid changes in their interactions with the surrounding solvent. Here...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2022
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9164226/ https://www.ncbi.nlm.nih.gov/pubmed/35580274 http://dx.doi.org/10.1021/jacs.2c01208 |
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author | Phelps, Ryan Orr-Ewing, Andrew J. |
author_facet | Phelps, Ryan Orr-Ewing, Andrew J. |
author_sort | Phelps, Ryan |
collection | PubMed |
description | [Image: see text] The photoexcitation of α-diazocarbonyl compounds produces singlet carbene intermediates that react with nucleophilic solvent molecules to form ylides. The zwitterionic nature of these newly formed ylides induces rapid changes in their interactions with the surrounding solvent. Here, ultrafast time-resolved infrared absorption spectroscopy is used to study the ylide-forming reactions of singlet carbene intermediates from the 270 nm photoexcitation of ethyl diazoacetate in various solvents and the changes in the subsequent ylide–solvent interactions. The results provide direct spectroscopic observation of the competition between ylide formation and C–H insertion in reactions of the singlet carbene with nucleophilic solvent molecules. We further report the specific solvation dynamics of the tetrahydrofuran (THF)-derived ylide (with a characteristic IR absorption band at 1636 cm(–1)) by various hydrogen-bond donors and the coordination by lithium cations. Hydrogen-bonded ylide bands shift to a lower wavenumber by −19 cm(–1) for interactions with ethanol, −14 cm(–1) for chloroform, −10 cm(–1) for dichloromethane, −9 cm(–1) for acetonitrile or cyclohexane, and −16 cm(–1) for Li(+) coordination, allowing the time evolution of the ylide–solvent interactions to be tracked. The hydrogen-bonded ylide bands grow with rate coefficients that are close to the diffusional limit. We further characterize the specific interactions of ethanol with the THF-derived ylide using quantum chemical (MP2) calculations and DFT-based atom-centered density matrix propagation trajectories, which show preferential coordination to the α-carbonyl group. This coordination alters the hybridization character of the ylidic carbon atom, with the greatest change toward sp(2) character found for lithium-ion coordination. |
format | Online Article Text |
id | pubmed-9164226 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-91642262022-06-05 Direct Observation of the Dynamics of Ylide Solvation by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy Phelps, Ryan Orr-Ewing, Andrew J. J Am Chem Soc [Image: see text] The photoexcitation of α-diazocarbonyl compounds produces singlet carbene intermediates that react with nucleophilic solvent molecules to form ylides. The zwitterionic nature of these newly formed ylides induces rapid changes in their interactions with the surrounding solvent. Here, ultrafast time-resolved infrared absorption spectroscopy is used to study the ylide-forming reactions of singlet carbene intermediates from the 270 nm photoexcitation of ethyl diazoacetate in various solvents and the changes in the subsequent ylide–solvent interactions. The results provide direct spectroscopic observation of the competition between ylide formation and C–H insertion in reactions of the singlet carbene with nucleophilic solvent molecules. We further report the specific solvation dynamics of the tetrahydrofuran (THF)-derived ylide (with a characteristic IR absorption band at 1636 cm(–1)) by various hydrogen-bond donors and the coordination by lithium cations. Hydrogen-bonded ylide bands shift to a lower wavenumber by −19 cm(–1) for interactions with ethanol, −14 cm(–1) for chloroform, −10 cm(–1) for dichloromethane, −9 cm(–1) for acetonitrile or cyclohexane, and −16 cm(–1) for Li(+) coordination, allowing the time evolution of the ylide–solvent interactions to be tracked. The hydrogen-bonded ylide bands grow with rate coefficients that are close to the diffusional limit. We further characterize the specific interactions of ethanol with the THF-derived ylide using quantum chemical (MP2) calculations and DFT-based atom-centered density matrix propagation trajectories, which show preferential coordination to the α-carbonyl group. This coordination alters the hybridization character of the ylidic carbon atom, with the greatest change toward sp(2) character found for lithium-ion coordination. American Chemical Society 2022-05-17 2022-06-01 /pmc/articles/PMC9164226/ /pubmed/35580274 http://dx.doi.org/10.1021/jacs.2c01208 Text en © 2022 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Phelps, Ryan Orr-Ewing, Andrew J. Direct Observation of the Dynamics of Ylide Solvation by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy |
title | Direct
Observation of the Dynamics of Ylide Solvation
by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy |
title_full | Direct
Observation of the Dynamics of Ylide Solvation
by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy |
title_fullStr | Direct
Observation of the Dynamics of Ylide Solvation
by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy |
title_full_unstemmed | Direct
Observation of the Dynamics of Ylide Solvation
by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy |
title_short | Direct
Observation of the Dynamics of Ylide Solvation
by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy |
title_sort | direct
observation of the dynamics of ylide solvation
by hydrogen-bond donors using time-resolved infrared spectroscopy |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9164226/ https://www.ncbi.nlm.nih.gov/pubmed/35580274 http://dx.doi.org/10.1021/jacs.2c01208 |
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