Benchmark Ab Initio Calculations of the Barrier Height and Transition-State Geometry for Hydrogen Abstraction from a Phenolic Antioxidant by a Peroxy Radical and Its Use to Assess the Performance of Density Functionals

2012 ◽  
Vol 3 (19) ◽  
pp. 2834-2839 ◽  
Author(s):  
Oksana Tishchenko ◽  
Donald G. Truhlar
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Barrier Height ◽  
Hydrogen Abstraction ◽  
Peroxy Radical ◽  
Phenolic Antioxidant ◽  
Density Functionals ◽  
Transition State Geometry

A study of hydrogen abstraction reactions by halogen atoms with HFCO and HClCO: determination of transition state structures, barrier heights, and vibrational frequencies

1993 ◽  
Vol 71 (1) ◽  
pp. 135-140 ◽  
Author(s):  
J. S. Francisco ◽  
N. Mina-Camilde
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chlorine Atom ◽  
Fluorine Atom ◽  
Hydrogen Abstraction ◽  
Barrier Heights ◽  
Optimized Geometries ◽  
Good Agreement

Theoretical barriers and reaction energetics were determined using ab initio calculations at the PMP4/6-311 + +G** level with UMP2/6-311G** optimized geometries for hydrogen abstraction reactions of HFCO and HClCO by fluorine and chlorine atoms. The largest barriers are predicted for fluorine and chlorine atom abstractions of hydrogen from HFCO. Fluorine and chlorine atom abstractions of hydrogen from HClCO are predicted to be barrierless. The predicted barrier for fluorine atom abstraction of hydrogen from HFCO is calculated to be 1.3 kcal mol−1 and is in good agreement with the experimental value of 1.8 ± 0.4 kcal mol−1.

Ab Initio Calculations for Hydrocarbons:  Enthalpy of Formation, Transition State Geometry, and Activation Energy for Radical Reactions

2003 ◽  
Vol 107 (43) ◽  
pp. 9147-9159 ◽  
Author(s):  
Mark Saeys ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin ◽  
Veronique Van Speybroeck ◽  
Michel Waroquier
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Enthalpy Of Formation ◽  
Radical Reactions ◽  
Transition State Geometry

scholarly journals Structural Parameters and Internal Rotational Barriers of tert-Butylammonium Ion: AM1 and ab initio Calculations

1992 ◽  
Vol 47 (12) ◽  
pp. 1255-1256
Author(s):  
Hiroyuki Ishida ◽  
Yoshihiro Kubozono ◽  
Setsuo Kashino ◽  
Ryuichi Ikeda
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Internal Rotation ◽  
Barrier Height ◽  
Structural Parameters ◽  
Mo Calculations ◽  
Ab Initio Mo Calculations ◽  
Rotational Barriers ◽  
Ab Initio Mo ◽  
Internal Rotational Barriers

Semiempirical and ab initio MO calculations were performed to estimate the structural parameters of tert-butylammonium ion and its potential energies for the internal rotation of the CH3 and NH3+ groups. The barrier height for the rotation of NH3+ was found to be lower than for that of CH3 , corresponding to the C - N bond being longer than the C - C bond.

Nitro–Nitrite Isomerization and Transition State Switching in the Dissociation of Ionized Nitromethane: A Threshold Photoelectron–Photoion Coincidence Spectroscopy Study

2009 ◽  
Vol 15 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Brandon Ferrier ◽  
Anne-Marie Boulanger ◽  
David M.P. Holland ◽  
David A. Shaw ◽  
Paul M. Mayer
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Bond Cleavage ◽  
Cleavage Reaction ◽  
Nitrite Ion ◽  
Methyl Nitrite ◽  
Bond Cleavage Reaction ◽  
Entropy Of Activation ◽  
Lower Entropy

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been employed to investigate the competition between bond cleavage and rearrangement reactions in the dissociation of ionized nitromethane, 1. Modeling TPEPICO breakdown diagrams with a combination of RRKM theory and ab initio calculations at the G3 level of theory allowed the derivation of the activation energy for the isomerisation of 1 to ionized methyl nitrite, 2, 82 kJ mol−1. In addition, evidence was found for a transition state switch in the bond cleavage reaction in 1 leading to CH3• + NO2+. As internal energy increases, the effective transition state for this reaction becomes tighter (i.e. is characterized by a lower entropy of activation, Δ‡S). Fitted thresholds for NO+ and CH2OHO+ ions, originating from the isomeric methyl nitrite ion, are consistent with G3 level ab initio calculations.

scholarly journals Conformational study on the structures and energies of the weakly bound complexes of AlCl3 with diatomic molecules

2007 ◽  
Vol 5 (4) ◽  
pp. 1007-1018 ◽  
Author(s):  
Issac Jimenez-Fabian ◽  
Abraham Jalbout ◽  
Abderahim Boutalib
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Conformational Study ◽  
Weakly Bound ◽  
Hydrogen Halides ◽  
Strength Of Interaction ◽  
Weakly Bound Complexes ◽  
Aluminium Trichloride ◽  
High Level

AbstractIn this work we present the results of high level ab initio calculations on weakly bound complexes of aluminium trichloride and hydrogen halides, HX, halogens, X2 and diatomic interhalogens, XY (where X, Y = F, Cl, Br). Based upon these calculations we have predicted that all structures in the staggered conformation (except for Cl3AlFH and Cl3AlClH) are stable minima while those in the eclipsed configurations are transition state structures. In the XH complexes the strength of interaction with the Cl3Al group is FH > ClH > BrH. In the case of X2 species it is Br2 > F2 > Cl2, and finally in the XY (YX) group it is: FBr > ClBr > FCl > BrCl > BrF > ClF.

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