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Ventura E, Rodrigues GP, Leitão EFV, do Monte SA. Theoretical Study of an Authentic Hydrocarbon Ion Pair. ACS OMEGA 2024; 9:34981-34989. [PMID: 39157103 PMCID: PMC11325399 DOI: 10.1021/acsomega.4c04914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 07/17/2024] [Accepted: 07/22/2024] [Indexed: 08/20/2024]
Abstract
For many years researchers believed that hydrocarbons only contain covalent bonds. However, since 1985 Okamoto et al. demonstrated the formation of hydrocarbon salts in several systems, demolishing the structural principle that hydrocarbons only contain covalent bonds. Despite the great importance of this outcome to the study of chemical bonds, quantum chemical calculations on these systems are essentially nonexistent. The stability of the hydrocarbon ions along with the steric hindrance associated with the formation of the covalent bond contribute to their occurrence either in solution (dissociated) or in the solid state. These facts along with the common formation of ion pairs in solvents of low polarity motivated us to search for hydrocarbon ion pairs in the gas phase. Its energetics has also been studied in four nonprotic solvents, through a continuum solvation model (CPCM). DFT and CASSCF calculations indicate a metastable and highly polar ion pair between the tricyclopropylcyclopropenylium cation and a simplified Kuhn's anion. The barrier to the covalent structure varies from ∼4.8 to 14.4 kcal/mol, while the energy difference between the ion pair and the covalent form varies from ∼4.3 to 25.4 kcal/mol. The obtained theoretical results along with previous experimental results suggest the following strategy to obtain kinetically and thermodynamically stable hydrocarbon ion pairs: choose very stable hydrocarbon ions and systematically increase the steric hindrance between them.
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Affiliation(s)
- Elizete Ventura
- Departamento
de Química, CCEN, Universidade Federal
da Paraíba, 58059-900 João Pessoa, Brazil
| | | | - Ezequiel Fragoso Vieira Leitão
- Unidade
Acadêmica de Ciências Exatas e da Natureza, Universidade Federal de Campina Grande, Cajazeiras, PB 58900-000, Brazil
| | - Silmar Andrade do Monte
- Departamento
de Química, CCEN, Universidade Federal
da Paraíba, 58059-900 João Pessoa, Brazil
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King KE, Franke PR, Pullen GT, Schaefer HF, Douberly GE. Helium Droplet Infrared Spectroscopy of the Butyl Radicals. J Chem Phys 2022; 157:084311. [DOI: 10.1063/5.0102287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Butyl radicals ( n-, s-, i-,} and tert-butyl) are formed from the pyrolysis of stable precursors (1-pentyl nitrite, 2-methyl-1-butyl nitrite, isopentyl nitrite, and azo- tert-butane, respectively). The radicals are doped into a beam of liquid helium droplets and probed with infrared action spectroscopy from 2700-3125 cm-1, allowing for a low temperature measurement of the CH stretching region. The presence of anharmonic resonance polyads in the 2800-3000 cm-1 region complicates its interpretation. To facilitate spectral assignment, the anharmonic resonances are modeled with two model Hamiltonian approaches that explicitly couple CH stretch fundamentals to HCH bend overtones and combinations: a VPT2+K normal mode model based on CCSD(T) quartic force fields and a semi-empirical local mode model. Both of these computational methods provide generally good agreement with the experimental spectra.
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Affiliation(s)
- Kale E King
- University of Georgia, United States of America
| | | | | | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, University of Georgia, United States of America
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, United States of America
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3
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Wagner JP. An Intramolecular Hydrogen-Shift in a Peroxy Radical at Cryogenic Temperatures: The Reaction of 2-Hydroxyphenyl Radical with O 2. Chemistry 2020; 26:12119-12124. [PMID: 32427391 DOI: 10.1002/chem.202000980] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Indexed: 11/08/2022]
Abstract
Peroxy radical hydrogen-shifts are pivotal elementary reaction steps in the oxidation of small hydrocarbons in autoignition and the lower atmosphere. Although these reactions are typically associated with a substantial barrier, we demonstrate that the [1,5]H-shift in the peroxy species derived from the 2-hydroxyphenyl radical 1 is so facile that it even proceeds rapidly in an argon matrix at 35 K through a proton-coupled electron transfer mechanism. Hydrogen-bound complexes of o-benzoquinone are identified as the main reaction products by infrared spectroscopy although their formation through O-O bond scission is hampered by a barrier of 11.9 kcal mol-1 at the ROCCSD(T)/cc-pVTZ/UB3LYP/6-311G(d,p) level of theory.
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Affiliation(s)
- J Philipp Wagner
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
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4
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Brown AR, Brice JT, Franke PR, Douberly GE. Infrared Spectrum of Fulvenallene and Fulvenallenyl in Helium Droplets. J Phys Chem A 2019; 123:3782-3792. [DOI: 10.1021/acs.jpca.9b01661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alaina R. Brown
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Joseph T. Brice
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Peter R. Franke
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
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5
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Franke PR, Brice JT, Moradi CP, Schaefer HF, Douberly GE. Ethyl + O2 in Helium Nanodroplets: Infrared Spectroscopy of the Ethylperoxy Radical. J Phys Chem A 2019; 123:3558-3568. [DOI: 10.1021/acs.jpca.9b01867] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Brown AR, Franke PR, Douberly GE. Helium Nanodroplet Isolation of the Cyclobutyl, 1-Methylallyl, and Allylcarbinyl Radicals: Infrared Spectroscopy and Ab Initio Computations. J Phys Chem A 2017; 121:7576-7587. [DOI: 10.1021/acs.jpca.7b07852] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alaina R. Brown
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, United States
| | - Peter R. Franke
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, United States
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, United States
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7
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Leicht D, Kaufmann M, Pal N, Schwaab G, Havenith M. From the tunneling dimer to the onset of microsolvation: Infrared spectroscopy of allyl radical water aggregates in helium nanodroplets. J Chem Phys 2017; 146:114306. [DOI: 10.1063/1.4978482] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel Leicht
- Department of Physical Chemistry II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Matin Kaufmann
- Department of Physical Chemistry II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Nitish Pal
- Department of Physical Chemistry II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Gerhard Schwaab
- Department of Physical Chemistry II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-Universität Bochum, 44780 Bochum, Germany
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Franke PR, Tabor DP, Moradi CP, Douberly GE, Agarwal J, Schaefer HF, Sibert EL. Infrared laser spectroscopy of the n-propyl and i-propyl radicals: Stretch-bend Fermi coupling in the alkyl CH stretch region. J Chem Phys 2016; 145:224304. [DOI: 10.1063/1.4971239] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Peter R. Franke
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Daniel P. Tabor
- Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Jay Agarwal
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Edwin L. Sibert
- Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Kaufmann M, Leicht D, Havenith M, Broderick BM, Douberly GE. Infrared Spectroscopy of the Tropyl Radical in Helium Droplets. J Phys Chem A 2016; 120:6768-73. [PMID: 27531683 DOI: 10.1021/acs.jpca.6b06522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matin Kaufmann
- Department of Physical Chemistry II, Ruhr-University Bochum , 44801 Bochum, Germany
| | - Daniel Leicht
- Department of Physical Chemistry II, Ruhr-University Bochum , 44801 Bochum, Germany
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum , 44801 Bochum, Germany
| | - Bernadette M Broderick
- Department of Chemistry, University of Georgia , Athens, Georgia 30602-2556, United States
| | - Gary E Douberly
- Department of Chemistry, University of Georgia , Athens, Georgia 30602-2556, United States
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Habig D, Leicht D, Schwaab G, Havenith M. Reassignment of ν2,3 IR band of the allyl radical in liquid helium nanodroplets. J Chem Phys 2015; 143:024308. [DOI: 10.1063/1.4923214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel Habig
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Daniel Leicht
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Gerhard Schwaab
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
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Broderick BM, McCaslin L, Moradi CP, Stanton JF, Douberly GE. Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene. J Chem Phys 2015; 142:144309. [DOI: 10.1063/1.4917421] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
| | - Laura McCaslin
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | | | - John F. Stanton
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
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12
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Complexation of Allyl Radicals and Hydrochloric Acid in Helium Nanodroplets. J Phys Chem A 2015; 119:1007-12. [DOI: 10.1021/jp511708s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Habig D, Leicht D, Kaufmann M, Schwaab G, Havenith M. IR-spectroscopic study of the allyl + NO reaction in helium nanodroplets. J Chem Phys 2014; 141:044312. [DOI: 10.1063/1.4890366] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel Habig
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Daniel Leicht
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Matin Kaufmann
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Gerhard Schwaab
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
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