Hydrogen tunneling avoided: enol-formation from a charge-tagged phenyl pyruvic acid derivative evidenced by tandem-MS, IR ion spectroscopy and theory
| Autor: | Jörg M. Neudörfl, Albrecht Berkessel, Anthony J. H. M. Meijer, Mathias Schäfer, Mathias Paul, Jos Oomens, Katrin Peckelsen, Thomas Thomulka, Giel Berden, Jonathan Martens |
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| Přispěvatelé: | Molecular Spectroscopy (HIMS, FNWI) |
| Rok vydání: | 2019 |
| Předmět: |
FELIX Molecular Structure and Dynamics
chemistry.chemical_classification Hydrogen Collision-induced dissociation Chemistry General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Photochemistry 01 natural sciences Aldehyde Enol Tautomer 0104 chemical sciences Ion chemistry.chemical_compound Excited state Physical and Theoretical Chemistry 0210 nano-technology Spectroscopy |
| Zdroj: | PCCP Physical Chemistry Chemical Physics, 21, 16591-16600 Physical Chemistry Chemical Physics, 21(30), 16591-16600. Royal Society of Chemistry PCCP Physical Chemistry Chemical Physics, 21, 30, pp. 16591-16600 |
| ISSN: | 1463-9076 |
| DOI: | 10.1039/c9cp02316j |
| Popis: | A charge-tagged phenyl pyruvic acid derivative was investigated by tandem-MS, infrared (IR) ion spectroscopy and theory. The tailor-made precursor ions efficiently lose CO2 in collision induced dissociation (CID) experiments, offering access to study the secondary decay reactions of the product ions. IR ion spectroscopy provides evidence for the formation of an enol acid precursor ion structure in the gas phase and indicates the presence of enol products formed after CO2 loss. Extensive DFT computations however, suggest intermediate generation of hydroxycarbene products, which in turn rearrange in a secondary process to the enol ions detected by IR ion spectroscopy. Quantum mechanical tunneling of the hydroxycarbene can be excluded since no evidence for aldehyde product ion formation could be found. This finding is in contrast to the behavior of methylhydroxycarbene, which cleanly penetrates the energy barrier to form exclusively acetaldehyde at cryogenic temperatures in an argon matrix via quantum mechanical hydrogen tunneling. The results presented here are attributed to the highly excited energy levels of the product ions formed by CID in combination with different barrier heights of the competing reaction channels, which allow exclusive access over one energy barrier leading to the formation of the enol tautomer ions observed. |
| Databáze: | OpenAIRE |
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