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Author(s):   Hou, X.J.; Nguyen, T.L.; Carl, S.A.; Peeters, J.; Nguyen, M.T.
Title:   Theoretical study of the kinetics of hydrogen abstraction in reactions of simple hydrogen compounds with triplet difluorocarbene
Journal:   Chem. Physl. Lett.
Volume:   402
Page(s):   460 - 467
Year:   2005
Reference type:   Journal article
Squib:   2005HOU/NGU460-467

Reaction:   CF2-trip + HBr·CHF2 + Br·
Reaction order:   2
Temperature:   298 - 800 K
Rate expression:   6.38x10-14 [cm3/molecule s] (T/298 K)2.30 e3675 [J/mole]/RT
Category:  Theory
Data type:   Ab initio
Pressure dependence:   Rate constant is pressure independent
Comments:   Calculated rate expressions for H-atom abstraction by CF2-triplet from H2, HF, HCl, HBr, H2O, H2S, NH3, PH3, CH4.

Use ab initio methods to compute transition states. Geometries CCSD(T)/6-311++G(d,p). Frequencies MP2/6-311++G(d,p). Energies CCSD(T)/6-311++G(3df,2p). Transition states were essentially linear C-H-X.

Rate expressions derived from ab initio transition states using conventional transition state theory calculations. Tunneling correction applied using an asymmetrical Eckart potential function.

Reactions with HF (~80 kJ/mol), H2O (~40 kJ/mol), H2 (~30 kJ/mol), CH4 (~25 kJ/mol), NH3 (~15 kJ/mol) had modest barriers. All others had barriers of less than 10 kJ/mol.

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Rate constant values calculated from the Arrhenius expression:

T (K)k(T) [cm3/molecule s]
298 2.81E-13
300 2.83E-13
350 3.26E-13
400 3.79E-13
450 4.39E-13
500 5.08E-13
550 5.83E-13
600 6.66E-13
650 7.57E-13
700 8.55E-13
750 9.61E-13
800 1.07E-12