Heats of Formation of Hydrofluorocarbons Obtained by Gaussian-3 and Related Quantum Chemical Computations

2000 ◽  
Vol 104 (32) ◽  
pp. 7600-7611 ◽  
Author(s):  
Naomi L. Haworth ◽  
Michael H. Smith ◽  
George B. Bacskay ◽  
John C. Mackie
Keyword(s):  
Quantum Chemical ◽  
Heats Of Formation ◽  
Quantum Chemical Computations

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.

Excitons in poly(para phenylene vinylene): a quantum-chemical perspective based on high-level ab initio calculations

2016 ◽  
Vol 18 (4) ◽  
pp. 2548-2563 ◽  
Author(s):  
Stefanie A. Mewes ◽  
Jan-Michael Mewes ◽  
Andreas Dreuw ◽  
Felix Plasser
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Phenylene Vinylene ◽  
High Level ◽  
Quantum Chemical Computations

Exciton analyses of high-level quantum-chemical computations for poly(paraphenylene vinylene) reveal the nature of the excitonic bands in PPV oligomers.

Methylamination of some 3,6-dinitro-1,8-naphthyridines with liquid methylamine – potassium permanganate

2000 ◽  
Vol 78 (7) ◽  
pp. 950-956
Author(s):  
Marian Wozniak ◽  
Maria Grzegozek ◽  
Piotr Surylo
Keyword(s):  
Quantum Chemical Calculations ◽  
Potassium Permanganate ◽  
Satisfactory Agreement ◽  
Quantum Chemical ◽  
Transition States ◽  
Molecular Orbitals ◽  
Heats Of Formation ◽  
Convenient Synthesis

3,6-Dinitro-1,8-naphthyridine and its 2-substituted derivatives are dehydro-methylaminated with the solution of potassium permanganate in liquid methylamine (LMA–PP) to the corresponding mono- or mono- and bis(methylamino)-3,6-dinitro-1,8-naphthyridines. In the case of 2-chloro- and 2-methoxy-3,6-dinitro-1,8-naphthyridine the replacement of chloro and methoxy substituents by the NHCH3 group occurs as well. Quantum-chemical calculations indicate the reactions to be controlled by the interaction of the frontal molecular orbitals (FMO) of the reagents. Moreover the heats of formation of intermediary methylamino-σ-adducts and transition states are calculated for the reaction studied. The calculations show satisfactory agreement between calculated and observed results. A convenient synthesis of some 2-substituted-3,6-dinitro-1,8-naphthyridines is reported.Key words: methylaminations, calculations PM3, nitro-1,8-naphthyridines, oxidation.

Exploring photochemistry of p-bromophenylsulfonyl, p-tolylsulfonyl and methylsulfonyl azides by ultrafast UV-pump–IR-probe spectroscopy and computations

2016 ◽  
Vol 18 (12) ◽  
pp. 8662-8672 ◽  
Author(s):  
A. V. Kuzmin ◽  
C. Neumann ◽  
L. J. G. W. van Wilderen ◽  
B. A. Shainyan ◽  
J. Bredenbeck
Keyword(s):  
Quantum Chemical ◽  
Time Resolved ◽  
Probe Spectroscopy ◽  
Quantum Chemical Computations

The photochemistry of three sulfonylazides was studied by femtosecond time-resolved infrared (TRIR) spectroscopy and quantum chemical computations.

Quantum chemical computations on rotational isomers of hydrogen nitrite and nitritomethane

1982 ◽  
Vol 381 (1781) ◽  
pp. 443-455 ◽  
Keyword(s):  
Excited States ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Basis Set ◽  
Electronic Transitions ◽  
Rotational Isomers ◽  
Transition Structures ◽  
Quantum Chemical Computations ◽  
Split Valence ◽  
Good Agreement

Ab initio molecular-orbital computations with a split-valence 4-31G basis set have been carried out on syn- and antiperiplanar conformers of both HONO and H 3 CONO, and on the transition structures in the unimolecular isomerization process. Calculated values of geometric structural and rotational parameters, dipole moments, wavenumbers of vibrational transitions, energies of vertical electronic transitions to both neutral and ionized excited states, and thermodynamic properties are compared with experimental data; generally good agreement is found. No explanation of the anomalous stability of antiperiplanar HONO has been discovered.

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