- Thermally persistent fluorosulfonyl nitrene and unexpected formation of the fluorosulfonyl radical
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Thermally persistent triplet sulfonyl nitrene, FSO2N, was produced in the gas phase in high yields (up to 66%) by flash vacuum pyrolysis of FSO2N3. Surprisingly, no rearrangement of FSO 2N was observed, but the
- Zeng, Xiaoqing,Beckers, Helmut,Willner, Helge
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p. 2096 - 2099
(2013/04/23)
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- Ionization Energies, Appearance Energies, and Thermochemistry of CF2O and FCO
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With the discharge flow-photoionization mass spectrometer (DF-PIMS) coupled to the U-11 beamline at the National Synchrotron Light Source, we have measured the ionization energies of C2F4, CF2, and CF2O and appearance energy of FCO+ from CF2O.The PIMS results corroborate those determined by other techniques.With high-level ab initio calculations that utilize a large basis set and isogyric corrections, we have determined an ionization energy of 9.3 +/- 0.1 eV for FCO.At 298 K, the heats of formation of FCO (-152 +/- 12 kJ/mol) and FCO+ (745.3 +/- 9.6 kJ/mol) fH0298(CF2O) = -607.9 +/- 7.1 kJ/mol> were determined and agree to within the uncertainties of other measurements but with much higher precision.We have evaluated the bond strengths D0298(F-CFO) and D0298(F-CO) to be 535 +/- 12 and 121 +/- 12 kJ/mol, respectively.
- Buckley, T. J.,Johnson, R. D.,Huie, R. E.,Zhang, Z.,Kuo, S.C.,Klemm, R. B.
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p. 4879 - 4885
(2007/10/02)
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- Gas-phase reactions of oxide and superoxide anions with CF4, CF3Cl, CF3Br, CF3I, and C2F4 at 298 and 500 K
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Rate constants and product branching fractions have been measured for the gas-phase reactions of oxide (O-) and superoxide (O2-) anions with the halocarbons CF4, CF3Cl, CF3Br, CF3I, and C2F4 using a variable temperature-selected ion flow tube (VT-SIFT) instrument operated at 298 and 500 K.The reactions of O- with CF3X (X = Cl, Br, I) are fast and produce F-, XF-, and XO- for all X.For CF3Cl and CF3Br, X- is also formed.For CF3I, CF3- and IOF- are minor products.O- reacts rapidly with C2F4 producing F- as the major ionic product, along with contributions from reactive detachment and minor formation of FCO-, CF3-, and C2F3O-.The reaction of O2- with CF3Cl is slow, and both clustering and X- formation were observed.For CF3Br and CF3I, the reactions with O2- are fast, and nondissociative charge transfer was observed in addition to X- formation.O2- reacts rapidly with C2F4 by reactive detachment, in addition to producing F- as the major ionic product with smaller amounts of F2-, FCO-, FCO2-, CF3O-, and C2F4O-.O- and O2- were both found to be unreactive with CF4 at 298 and 500 K.The efficiencies of the reactions of both O- and O2- with CF3X are greater for the heavier halides at both 298 and 500 K.The rate constants for the reactions of O2- with CF3X appear to correlate both with the rates of thermal electron attachment to CF3X and with the electron affinities of CF3X, indicating that the O2- + CF3X reaction mechanism may involve initial electron transfer followed by dissociation.Thus the negative electron affinity of CF3Cl may explain the very slow rate for reaction with O2- despite the available exothermic pathways.
- Morris, Robert A.
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p. 2372 - 2381
(2007/10/02)
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- The reaction of atomic fluorine with formyl fluoride: An experimental and theoretical study
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The rate coefficient for the reaction of F + HFCO has been determined over the temperature range 298-368 K by monitoring the appearance rate of HF infrared chemiluminescence using the infrared multiphoton dissociation-infrared chemiluminescence technique.Results, expressed in the Arrhenius form k(T) = 4.4 +/- 2.6x10-11 exp cm3 molecule-1s-1, are compared with the barrier height calculated using ab initio molecular orbital theory.The rate coefficient is theoretically discussed with the aid of essential features of the potential energy surface for the F + HFCO system and the potential importance of the reaction is considered.A rate coefficient for deactivation of excited HF by HFCO is reported as 1.2 +/- 0.2x10-12 cm3 molecule -1s-1.
- Francisco, J. S.,Zhao, Y.
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p. 276 - 286
(2007/10/02)
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- Emission from FCO in the Reactions of Ozone with Fluoroethenes
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The gas-phase reactions of ozone with cis-1,2-difluoroethene, trans-1,2-difluoroethene, trifluoroethene, and chlorotrifluoroethene are all accompanied by light with a maximum intensity at approximately 425 nm.A partial vibrational analysis of this emission is presented and it is concluded that the emitting species is the FCO radical, as previously suggested.A comparison is made between the enthalpy changes of the primary reactions between ozone and the fluoroethenes and their correlation with the identity of the emitting species.The exothermicity of the reaction correlates with the chemiluminescent reaction channel.
- Toby, Sidney,Toby, Frina S.
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p. 4071 - 4073
(2007/10/02)
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