Thermochemistry of inorganic solids. 10. Empirical relations between the enthalpies of formation of solid halides and the corresponding gas-phase halide anions

1992 ◽  
Vol 37 (2) ◽  
pp. 194-199 ◽  
Author(s):  
Mohamed W. M. Hisham ◽  
Sidney W. Benson
Keyword(s):  
Gas Phase ◽  
Enthalpies Of Formation ◽  
Inorganic Solids ◽  
Halide Anions ◽  
Empirical Relations

scholarly journals Standard Molar Enthalpies of Formation of Halomethanes Based on Quantum Chemical Computations

2020 ◽  
Author(s):  
Konstantinos Kalamatianos
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Halogen Bond ◽  
Chemical Processes ◽  
Enthalpies Of Formation ◽  
Isodesmic Reaction ◽  
Gold Standard Method ◽  
Ozone Destruction ◽  
Quantum Chemical Computations ◽  
Reaction Schemes

Accurate calculations of standard molar enthalpies of formation (ΔΗf°)m(g) and carbon-halogen bond dissociation enthalpies, BDE, of a variety of halomethanes with relevance on several atmospheric chemical processes and particularly to ozone destruction, were performed in the gas phase at 298.15 K. The (ΔΗf°)m(g) of the radicals formed through bond dissociations have also been computed. Ab initio computational methods and isodesmic reaction schemes were used. It is found that for the large majority of these species, the gold standard method of quantum chemistry (CCSD(T)) and even MP2 are capable to predict enthalpy values nearing chemical accuracy provided that isodesmic reaction schemes are used. New estimates for standard molar enthalpies of formation and BDE are suggested including for species that to our knowledge there are no experimental (ΔΗf°)m(g) (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) or BDE values (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) available in the literature. The method and calculational procedures presented may profitably be used to obtain accurate (ΔΗf°)m(g) and BDE values for these species.

scholarly journals Enthalpies of Combustion and Formation of Severely Crowded Methyl-Substituted 1,3-dioxanes. The Magnitudes of 2,4- and 4,6-diaxial Me,Me-Interactions and the Chair–2,5-twist Energy Difference

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2762 ◽  
Author(s):  
Kalevi Pihlaja ◽  
Henri Kivelä ◽  
Pirjo Vainiotalo ◽  
William V. Steele
Keyword(s):  
Gas Phase ◽  
Chair Conformation ◽  
Energy Difference ◽  
Enthalpies Of Formation ◽  
Methyl Groups ◽  
Chair Form ◽  
Twist Form

Enthalpies of combustion of 2,2-trans-4,6- (1) and 4,4,6,6-tetramethyl- (2) and 2,4,4,6,6- (3) and 2,2,4,4,6-pentamethyl-1,3-dioxanes (4) were determined to estimate their enthalpies of formation in the gas phase. By comparing the latter with the corresponding enthalpies estimated based on the various bond–bond interactions allowed to determine the chair–2,5-twist energy difference (ΔHCT = 29.8 kJ mol–1) for 1 since C-13 shift correlations indicate that it escapes to the 2,5-twist form where the 2-methyl groups are isoclinal and 4- and 6-methyl groups pseudoequatorial to avoid syn-axial interactions. Compounds 2 and 3 in turn give the values 21.0 and 21.6 kJ mol–1 for the 4,6-diaxial Me,Me-interaction. Finally compound 4, which retains the chair conformation to avoid pseudoaxial interactions in the twist forms gives the value 19.5 kJ mol–1 for the 2,4-diaxial Me,Me-interaction indicating that its chair form appears to be somewhat deformed.

The Enthalpies of Formation ofo-,m-, andp-Benzoquinone:  Gas-Phase Ion Energetics, Combustion Calorimetry, and Quantum Chemical Computations Combined

2005 ◽  
Vol 127 (16) ◽  
pp. 6116-6122 ◽  
Author(s):  
Alireza Fattahi ◽  
Steven R. Kass ◽  
Joel F. Liebman ◽  
M. Agostinha R. Matos ◽  
Margarida S. Miranda ◽  
...  
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Combustion Calorimetry ◽  
Enthalpies Of Formation ◽  
Gas Phase Ion ◽  
Quantum Chemical Computations
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