Infrared and EPR Spectroscopic Studies of 2-C2H2F and 1-C2H2F Radicals Isolated in Solid Argon

Goldschleger, Ilya U.; Акимов, А. В.; Misochko, Eugenii Ya.; Wight, Charles A.

doi:10.1006/jmsp.2000.8266

Cited by 17 publications

(7 citation statements)

References 26 publications

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“…In general, the major absorption features can be categorized into groups and associated with the argon‐isolated π‐complex of HF and ethyne (3745.4, 3280.7, 1398.7, 1347.2, 758.0, 739.6, 642.7 and 426.2 cm −1 ),6, 7 fluoroacetylene, HC≡CF (3357.7, 2240.2, 1056.9, 585.8 and 583.0 cm −1 ),7 cis ‐2‐fluoroethylene radical, c ‐HFCCH • (3025.5, 1631.8, 1263.2, 785.0, 677.4, 631.2 and 461.9 cm −1 ),10 1‐fluoroethylene radical, H 2 CCF • (1133.1 and 797.6 cm −1 )10 and the proton‐bound argon dimer cation, Ar 2 H + (904.1 cm −1 ) 11. Two major features were sometimes observed at 3714.1 and 410.7 cm −1 which appear to behave as additional sites of the HF/C 2 H 2 complex; however, further experimentation is required to confirm this identification.…”

Section: Resultsmentioning

confidence: 99%

“…The three isomers then have radical character on the carbon atom bearing the CF, or at the adjacent carbon placed cis ‐ or trans ‐relative to the CF bond. Of these three possible isomers, only the H 2 CCF • 10 and the cis ‐2‐HFCCH • 10 are observed in the EB‐MI difference infrared spectra, with no clear evidence of the trans ‐2‐HFCCH • species 10. Therefore, it seems that the H atom which dissociates from the initially formed VF cation is either the CH bond on the F‐containing carbon, or the CH bond on the cis ‐side of the VF molecule.…”

Section: Discussionmentioning

confidence: 99%

“…Thermochemically, the CH bond on the F‐containing carbon is that which is favored for bond cleavage,22, 23 and could be expected as the dominant cleavage mechanism in this work. However, since reversible photo‐induced inter‐conversion of the two radical isomers is also known,10 and given that the C 2 H 2 F + is neutralized in the matrix to form an initially vibrationally hot C 2 H 2 F • species, it is possible that a rapid H atom transfer could occur faster than the energy transfer to the surrounding matrix support. Therefore, it is not possible under the current conditions to conclude if a single CH bond cleavage is dominant in this system, or if the CH bond cleavage occurs competitively at both of these CH bonds from the VF parent ion.…”

Section: Discussionmentioning

confidence: 99%

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Electron‐bombardment matrix isolation and PEPICO studies as complementary techniques in ion chemistry: an FTIR study of the decomposition of the vinyl fluoride cation

Thompson¹,

Linford²,

Parnis³

2011

J. Mass Spectrom.

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FTIR spectra have been obtained for matrices formed following electron bombardment of gas mixtures containing varying amounts of vinyl fluoride (VF) in Ar (1:400 to 1:25,600; VF/Ar). The major matrix-isolated products are a π-complex of HF/C(2)H(2) , fluoroacetylene (HC≡CF) and two isomers of C(2)H(2)F(•). These products correspond well with the products of photoionization of VF near 15.8 eV. These observations support the dominant mechanism of ionization in the EB-MI environment as charge transfer of the substrate molecule to Ar(•+). Some differences are noted between the observed EB-MI products and the results from PEPICO studies, primarily in that the EB-MI products are observed as neutralized forms. The close correlation in EB-MI and photoionization results allows the EB-MI technique to be utilized as an ion structural analysis tool in complement to PEPICO studies, and allows the use of PEPICO studies to help predict and elucidate high-pressure chemistry mechanisms through EB-MI studies. The differences in the EB-MI results and ions observed using the PEPICO technique are rationalized in terms of the differences in the experimental techniques. Using VF as the test system, reagent partial pressure conditions that best complement PEPICO studies are determined. Although the major results are observed for all VF partial pressures, dilute samples give rise to further ionization of the primary products, and more concentrated samples give rise to radical-radical reaction chemistry. As a result, a nominal range of 1:3200 (VF/Ar) is demonstrated to provide the best correlation with the gas-phase PEPICO measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Electron‐bombardment matrix isolation and PEPICO studies as complementary techniques in ion chemistry: an FTIR study of the decomposition of the vinyl fluoride cation

Thompson¹,

Linford²,

Parnis³

2011

J. Mass Spectrom.

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“…16) and · CHCHF, 17,18 isolated in noblegas matrices were identified. These species were generated in noble-gas matrices via annealing-induced reactions or via co-deposition of C 2 H 2 and F atoms produced in a microwave discharge.…”

Section: Introductionmentioning

confidence: 99%

Reactions between chlorine atom and acetylene in solid para-hydrogen: Infrared spectrum of the 1-chloroethyl radical

Golec

Lee

2011

The Journal of Chemical Physics

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We applied infrared matrix isolation spectroscopy to investigate the reactions between Cl atom and acetylene (C₂H₂) in a para-hydrogen (p-H₂) matrix at 3.2 K; Cl was produced via photodissociation at 365 nm of matrix-isolated Cl₂ in situ. The 1-chloroethyl radical (·CHClCH₃) and chloroethene (C₂H₃Cl) are identified as the main products of the reaction Cl + C₂H₂ in solid p-H₂. IR absorption lines at 738.2, 1027.6, 1283.4, 1377.1, 1426.6, 1442.6, and 2861.2 cm⁻¹ are assigned to the 1-chloroethyl radical. For the reaction of Cl + C₂D₂, lines due to the ·CDClCH₂D radical and trans-CHDCDCl are observed; the former likely has a syn-conformation. These assignments are based on comparison of observed vibrational wavenumbers and ¹³C- and D-isotopic shifts with those predicted with the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ methods. Our observation indicates that the primary addition product of Cl + C₂H₂, 2-chlorovinyl (·CHCHCl) reacts readily with a neighboring p-H2 molecule to form ·CHClCH₃ and C₂H₃Cl. Observation of ·CDClCH₂D and trans-CHDCDCl from Cl + C₂D₂ further supports this conclusion. Although the reactivity of p-H₂ appears to be a disadvantage for making highly reactive free radicals in solid p-H₂, the formation of 1-chloroethyl radical indicates that this secondary reaction might be advantageous in producing radicals that are difficult to prepare from simple photolysis or bimolecular reactions in situ.

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“…In contrast to photolysis of isolated F 2 , photolysis of F 2 in binary M−F 2 complexes leads to closed-shell products in which all of the atoms are retained in the reaction cage Photochemical reactions of types 2a and 2b were studied earlier by infrared spectroscopy. ,− These reactions appeared to proceed directly, and no intermediates were observed. The possibility always exists for one of the F atoms to escape the reactant cage; in this case, we might expect the formation of a pair of stabilized radicals such as [FM • ···F • ] or [HF−R • ···F • ].…”

Section: Introductionmentioning

confidence: 99%

Photochemical Formation and Reaction of Radical Pairs from NH₃−F₂ Complexes Isolated in Solid Argon

Акимов¹,

Goldschleger²,

Misochko³

et al. 2002

J. Phys. Chem. A

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Photoinduced reactions in binary NH 3 -F 2 complexes in solid argon are studied by FTIR spectroscopy. Analysis of the IR spectra and kinetics of product formation shows that the main photochemical channel at 355 nm is the formation of [H 2 N • -HF‚‚‚F • ] radical pairs; the relative initial yield of this product is 0.55. We believe that this is the first observation of this mechanism of radical pair formation (i.e., by escape of one of the F atoms from the initial cage containing the complex). The other major product channels form FH 2 N-HF and NH-HF-HF complexes in approximately equal amounts. Isotopic substitution experiments using 15 NH 3 and ND 3 aided the assignments of the infrared bands of NH-HF-HF, which is identified for the first time. Thermal recombination of the [H 2 N • -HF‚‚‚F • ] radical pairs at 20 K yields only the addition product FH 2 N-HF. However, photoinduced recombination of [H 2 N • -HF‚‚‚F • ] radical pairs at 633, 532, 355, and 266 nm gives predominantly NH-HF-HF complexes. The relative yield of this secondary photolysis product increases with increasing energy of photoexcitation and is close to unity at λ e 355 nm.

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Infrared and EPR Spectroscopic Studies of 2-C2H2F and 1-C2H2F Radicals Isolated in Solid Argon

Cited by 17 publications

References 26 publications

Electron‐bombardment matrix isolation and PEPICO studies as complementary techniques in ion chemistry: an FTIR study of the decomposition of the vinyl fluoride cation

Electron‐bombardment matrix isolation and PEPICO studies as complementary techniques in ion chemistry: an FTIR study of the decomposition of the vinyl fluoride cation

Reactions between chlorine atom and acetylene in solid para-hydrogen: Infrared spectrum of the 1-chloroethyl radical

Photochemical Formation and Reaction of Radical Pairs from NH₃−F₂ Complexes Isolated in Solid Argon

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Infrared and EPR Spectroscopic Studies of 2-C2H2F and 1-C2H2F Radicals Isolated in Solid Argon

Cited by 17 publications

References 26 publications

Electron‐bombardment matrix isolation and PEPICO studies as complementary techniques in ion chemistry: an FTIR study of the decomposition of the vinyl fluoride cation

Electron‐bombardment matrix isolation and PEPICO studies as complementary techniques in ion chemistry: an FTIR study of the decomposition of the vinyl fluoride cation

Reactions between chlorine atom and acetylene in solid para-hydrogen: Infrared spectrum of the 1-chloroethyl radical

Photochemical Formation and Reaction of Radical Pairs from NH3−F2 Complexes Isolated in Solid Argon

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Photochemical Formation and Reaction of Radical Pairs from NH₃−F₂ Complexes Isolated in Solid Argon