Infrared spectroscopic investigation of propargyl radicals stabilized in low-temperature argon matrix

Королев, В. А.; Mal'tsev, A. K.; Нефедов, О. М.

doi:10.1007/bf00955425

Cited by 8 publications

(15 citation statements)

References 12 publications

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“…The lowest frequency transition detected is at 483 cm -1 (ν 7 ). Although others 14 have assigned this peak to ν 12 in the past, we identify the 483 cm -1 band with ν 7 on the basis of the electronic structure calculations as well as the depletion/LD spectra in Figure 8. The ν 7 mode corresponds to a CH out-of-plane-bend (b 1 ) which was observed earlier in the negative ion photodetachment spectra 7,8 at 490 ( 10 cm -1 .…”

Section: Resultsmentioning

confidence: 99%

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH₂

et al. 2005

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The propargyl radical has twelve fundamental vibrational modes, gamma(vib)(HCCCH2) = 5a1 [symbol: see text] 3b1 [symbol: see text] 4b2, and nine have been detected in a cryogenic matrix. Ab initio coupled-cluster anharmonic force field calculations were used to help guide some of the assignments. The experimental HC=:C-:CH2 matrix frequencies (cm(-1)) and polarizations are a1 modes--3308.5 +/- 0.5, 3028.3 +/- 0.6, 1935.4 +/- 0.4, 1440.4 +/- 0.5, 1061.6 +/- 0.8; b1 modes--686.6 +/- 0.4, 483.6 +/- 0.5; b2 modes--1016.7 +/- 0.4, 620 +/- 2. We recommend a complete set of gas-phase vibrational frequencies for the propargyl radical, HC=:C-:CH2 2 X (2)B1. From an analysis of the vibrational spectra, the small electric dipole moment, mu(D)(HCCCH2) = 0.150 D, and the large resonance energy (HCCCH2), roughly 11 kcal mol(-1), we conclude that propargyl is a completely delocalized hydrocarbon radical and is best written as HC=:C-:CH2.

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Section: Resultsmentioning

confidence: 99%

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH₂

et al. 2005

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“…16 Moreover, we introduce dipropargyl oxalate (DPO), HCCCH 2 O(O)C-C(O)OCH 2 CCH, as a new halogen-free photolytic source for propargyl radicals. This idea is based on earlier work using the thermal decomposition of diallyl [22][23][24] and dipropargyl 25 oxalate to produce the respective unsaturated radicals. With this precursor the above mentioned complications by simultaneously generated halogen atoms are avoided, and the spectroscopic features of C 3 H 3 are not obscured by halogen adducts.…”

Section: Pccpmentioning

confidence: 99%

“…Our idea to use the photolysis of dipropargyl oxalate for the production of propargyl radicals was essentially based on earlier work, [22][23][24] in which diallyl oxalate was used to thermolytically produce allyl radicals. Later we became aware of one work, 25 in which indeed the thermolysis of the dipropargyl ester was employed to generate propargyl radicals (for a matrix-isolation study). No information, however, is available on the kinetics and mechanism of this reaction.…”

Section: Dpo As C 3 H 3 Precursormentioning

confidence: 99%

The rate coefficient of the C₃H₃ + C₃H₃reaction from UV absorption measurements after photolysis of dipropargyl oxalate

Giri

Hippler

Olzmann

et al. 2003

Phys. Chem. Chem. Phys.

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The kinetics of the C 3 H 3 + C 3 H 3 reaction was investigated by using dipropargyl oxalate (DPO) as a new, halogen-free photolytic source for propargyl radicals in the gas phase. After laser-flash photolysis of DPO at 193 nm, the initial absorbance was determined at different wavelengths, and the results were compared with values obtained in analogous experiments using propargyl halides as precursors. A satisfactory agreement of the absorbances was found between 295 and 355 nm but differences were observed near 242 nm. The latter wavelength has also been proposed for C 3 H 3 detection. Our results, however, indicate that this absorption is probably due to halogen-containing species. The rate coefficient of the C 3 H 3 + C 3 H 3 reaction was then determined from time-resolved absorption measurements at 332.5 nm with DPO as precursor. Values of (2.7 AE 0.6) Â 10 À11 cm 3 molecule À1 s À1 at 373 K, (2.8 AE 0.6) Â 10 À11 cm 3 molecule À1 s À1 at 425 K, (3.5 AE 0.8) Â 10 À11 cm 3 molecule À1 s À1 at 500 K, and (4.1 AE 0.8) Â 10 À11 cm 3 molecule À1 s À1 at 520 K were obtained with no significant pressure dependence between 1 and ca. 100 bar (140 bar for T ¼ 373 K).

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“…However, because ethylene (C 2 H 4 ) has been observed in our spectra and it has a band near 3112 cm –1 , we did not assign this weak feature to ν 9 of propargyl due to the interference from ethylene. The ν 9 band was reported by Korolev et al in an Ar matrix at 3111 cm –1 . In their study, propargyl iodide was used as a pyrolysis precursor, and ethylene was not observed in the spectra.…”

Section: Resultsmentioning

confidence: 58%

“…Propargyl is one of the simplest delocalized hydrocarbon radicals and can be represented by (X̃ 2 B 1 ). , Recombination of propargyl radicals to produce benzene is considered to be one of the key reactions in generating aromatic species in both combustion and Titan’s atmosphere. , Due to its importance, several experimental studies have been conducted to determine the chemical and physical properties of propargyl, including its vibrational frequencies. − The (X̃ 2 B 1 ) radical has 12 vibrational modes (5a 1 ⊕ 3b 1 ⊕ 4b 2 ); all of them are IR-active. Of its 12 fundamental vibrational modes, 11 have been detected. ,− The low-frequency bending mode ν 12 , however, has not previously been observed.…”

Section: Introductionmentioning

confidence: 91%

Detection of the Far-IR ν₁₂ Bending Level in Propargyl: A Complete Set of Fundamentals for an Important Radical

2012

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Propargyl (HCCCH(2)) radicals have been generated by expanding precursors through a supersonic pyrolysis nozzle, and their infrared (IR) absorption spectra have been recorded in a rare gas matrix. Besides the 10 vibrational modes observed in our previous studies, this investigation detected the HCCCH(2) X̃ (2)B(1) in-plane bending mode (ν(12)) at 344.2 (±0.8) cm(-1) in a cryogenic argon matrix. This is the first experimental observation of ν(12) for the propargyl radical. In the previous study, ν(12) had been fixed at 333 (±10) cm(-1) based on detection of its overtone (2ν(12), 667.7 ± 1.0 cm(-1)) and a possible combination band (ν(10) + ν(12), 1339.0 ± 0.8 cm(-1)). The new observation is in reasonable agreement with this previous experimental estimation of ν(12). Ab initio coupled cluster anharmonic force field calculations were used to guide the analysis. Our finding completes the fundamental frequency database for propargyl.

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Infrared spectroscopic investigation of propargyl radicals stabilized in low-temperature argon matrix

Cited by 8 publications

References 12 publications

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH₂

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH₂

The rate coefficient of the C₃H₃ + C₃H₃reaction from UV absorption measurements after photolysis of dipropargyl oxalate

Detection of the Far-IR ν₁₂ Bending Level in Propargyl: A Complete Set of Fundamentals for an Important Radical

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Infrared spectroscopic investigation of propargyl radicals stabilized in low-temperature argon matrix

Cited by 8 publications

References 12 publications

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH2

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH2

The rate coefficient of the C3H3 + C3H3reaction from UV absorption measurements after photolysis of dipropargyl oxalate

Detection of the Far-IR ν12 Bending Level in Propargyl: A Complete Set of Fundamentals for an Important Radical

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Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH₂

Propargyl Radical: Ab Initio Anharmonic Modes and the Polarized Infrared Absorption Spectra of Matrix-Isolated HCCCH₂

The rate coefficient of the C₃H₃ + C₃H₃reaction from UV absorption measurements after photolysis of dipropargyl oxalate

Detection of the Far-IR ν₁₂ Bending Level in Propargyl: A Complete Set of Fundamentals for an Important Radical