G2 <i>ab</i> <i>initio</i> calculations of the enthalpy of formation of hydrazoic acid, methyl azide, ethyl azide, methyl amine, and ethyl amine

Rogers, Donald W.; McLafferty, Frank J.

doi:10.1063/1.470712

Cited by 14 publications

(15 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“… a The compound’s number according to Figure is given for each molecule. b Values calculated from isodesmic reactions are given. c Calculated from the ATcT reference value of the atomization energy, ref . d Calculated from the atomization energies computed at the fc-CCSD(T)/cc-pCVQZ//ae-CCSD(T)/cc-pCVTZ level (ref ) and by the W4 method (ref ). e The mean of the values derived from the reaction HN 3 + CH 2 N• → CH 2 NH + •N 3 using different CBS and G n composite methods, ref . f CCSD(T)/CBS, ref . g These values were obtained by different composite methods (ref ), different ab initio methods (ref ), and CCSD(T)/aug-cc-pVQZ calculations (ref ). h The mean of the values derived from the reaction CH 3 N 3 + CH 2 N• → CH 2 NCH 3 + •N 3 using different CBS and G n composite methods, ref . i G2 value, ref . j Assumed by analogy with 1,3-dinitrobenzene. k Recalculated in this study using D (NC–N 3 ) = 401.4 ± 9.6 kJ/mol (ref ), Δ f H 0 ° (CN, g) = 437 ± 5 kJ/mol (ref ), and Δ f H 0 ° (N 3 , g) = 453 ± 5 kJ/mol (this work). l This value corresponds to Δ f H 0 ° (NCN 3 , g) = 511 kJ/mol calculated by the G3 method (ref ). m Estimated from the boiling temperature. n MP2/aug-cc-pVDZ, combustion reaction, ref . o Assumed to be the same as that in azidocyclohexane. p Estimated in accordance with ref . q Estimated from an empirical correlation of the surface tension with the heat of vaporization. r Recalculated in this work using the experimental enthalpy of formation of 1-aminoadamantane, ref . s B3LYP/6-31G(d), isodesmic reaction, ref . t B3LYP/aug-cc-pVDZ, isodesmic reaction, ref . u Estimated using the Politzer approach, refs and . v B3LYP, HF, and MP2 calculations, isodesmic reaction, ref . w B3LYP/6-31G(d), isodesmic reaction, ref . x B3LYP/6-311++G(3d,3p), isodesmic reaction, ref . …”

Section: Resultsmentioning

confidence: 99%

Accurate Prediction of Enthalpies of Formation of Organic Azides by Combining G4 Theory Calculations with an Isodesmic Reaction Scheme

2013

View full text Add to dashboard Cite

Accurate gas-phase enthalpies of formation (Δf H 298 °) of 29 azides are recommended by combining G4 theory calculations with an isodesmic reaction approach. The internal consistency over a set of Δf H 298 ° values was achieved by sequential adjustment of their values through the isodesmic reactions. The HN3 was chosen as a key reference compound. Of the experimental data available for 16 compounds, our predictive values agree well with 9 of them, while the deviations from 25 to 55 kJ/mol are observed for 7 compounds; possible systematic errors in the experimental data for phenyl azide, 2-azidoethanol, azidocyclopentane, azidocyclohexane, 3-azido-3-ethylpentane, 2-azido-2-phenylpropane, and 1-azidoadamantane are discussed. The recommended enthalpies of formation of organic azides were used as reference values to estimate the enthalpy of formation of four nitrogen-rich carbon nitrides. The calculations do not support the high value of the solid-state enthalpy of formation of TAAT (4,4′,6,6′-tetra(azido)azo-1,3,5-triazine); its value is estimated to be 300–400 kJ/mol lower than that measured experimentally.

show abstract

Section: Resultsmentioning

confidence: 99%

Accurate Prediction of Enthalpies of Formation of Organic Azides by Combining G4 Theory Calculations with an Isodesmic Reaction Scheme

2013

View full text Add to dashboard Cite

show abstract

“…Moreover, signals due to HCN were also present, [17] weakly at 5008C, but strongly at 9008C. FWW interpreted this in terms of chemical activation of the methylenimine by 89 AE 5 kcal mol À1 arising from the activation energy for denitrogenation of azidomethane [18] ,38 AE 2 kcal mol À1 plus the exothermicity of the reaction ,51 AE 3 kcal mol -1 [19,20] (Eqns 1 and 2 and Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Chemical Activation in Azide and Nitrene Chemistry: Methyl Azide, Phenyl Azide, Naphthyl Azides, Pyridyl Azides, Benzotriazoles, and Triazolopyridines

Wentrup¹

2013

Aust. J. Chem.

View full text Add to dashboard Cite

Chemical activation (the formation of 'hot' molecules due to chemical reactions) is ubiquitous in flash vacuum thermolysis (FVT) reactions, and awareness of this phenomenon is indispensable when designing synthetically useful gas-phase reactions. Chemical activation is particularly prevalent in azide chemistry because the interesting singlet nitrenes are high-energy intermediates, and their reactions are highly exothermic. Consequently, chemical activation is observed in the isomerization of methylnitrene CH 3 N to methylenimine (methanimine) CH 2 ¼NH, facilitating the elimination of hydrogen to form HCN or HNC. Rearrangements of phenylnitrene, 1-and 2-naphthylnitrenes, and 2-, 3-and 4-pyridylnitrenes afford cyanocyclopentadiene, 3-and 2-cyanoindenes, and 2-and 3-cyanopyrroles, all showing the effects of chemical activation by undergoing facile interconversion of isomers. Chemical activation can often be reduced or removed entirely by increasing the pressure, thereby promoting collisional deactivation. Larger molecules having more degrees of freedom are better able to dissipate excess energy; therefore the effects of chemical activation are less pronounced or completely absent in the formation of 3-cyanoindole and 1-cyanobenzimidazoles from 3-and 4-quinolylnitrenes and 4-quinazolinylnitrenes, respectively. In compounds possessing nitro groups, chemical activation can cause the loss of the nitro group at nominal temperatures far below those normally needed to cleave the C-NO 2 bond.

show abstract

“…Ab initio or experimental enthalpies of formation can be located for only hydrazoic acid and methylazide 21. Comparing the ab initio numbers to those computed with B3LYP-LOC shows clearly superior performance when resonance structure (a), as opposed to (b), is utilized.…”

Section: Resultsmentioning

confidence: 99%

Localized Orbital Corrections for the Barrier Heights in Density Functional Theory

Hall

Goldfeld

Bochevarov

et al. 2009

J. Chem. Theory Comput.

View full text Add to dashboard Cite

This work describes the extension of a previously reported empirical localized orbital correction model for density functional theory (DFT-LOC) for atomization energies, ionization potentials, electron affinities, and reaction enthalpies to the correction of barrier heights for chemical reactions of various types including cycloadditions, cycloreversions, dipolar cycloadditions, S N 2′s, carbon radical reactions, hydrogen radical reactions, sigmatropic shifts, and electrocyclizations. The B3LYP localized orbital correction version of the model (B3LYP-LOC) reduces the number of outliers and overall mean unsigned error (MUE) vs. experiment or ab initio values from 3.2 to 1.3 kcal/mole for barrier heights and from 5.1 to 1.1 kcal/mole for reaction enthalpies versus B3LYP. Furthermore, the new model has essentially zero additional computational cost beyond standard DFT calculations. Although the model is heuristic and is based on multiple linear regression to experimental or ab initio data, each of the parameters is justified on chemical grounds and provides insight into the fundamental limitations of DFT, most importantly the failure of current DFT methods to accurately account for nondynamical electron correlation.

show abstract

G2 ab initio calculations of the enthalpy of formation of hydrazoic acid, methyl azide, ethyl azide, methyl amine, and ethyl amine

Abstract: Articles you may be interested inValence and ionic lowest-lying electronic states of ethyl formate as studied by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy, and ab initio calculations

Cited by 14 publications

References 10 publications

Accurate Prediction of Enthalpies of Formation of Organic Azides by Combining G4 Theory Calculations with an Isodesmic Reaction Scheme

Accurate Prediction of Enthalpies of Formation of Organic Azides by Combining G4 Theory Calculations with an Isodesmic Reaction Scheme

Chemical Activation in Azide and Nitrene Chemistry: Methyl Azide, Phenyl Azide, Naphthyl Azides, Pyridyl Azides, Benzotriazoles, and Triazolopyridines

Localized Orbital Corrections for the Barrier Heights in Density Functional Theory

Contact Info

Product

Resources

About