A discrepancy between experimental and theoretical thermochemical characterization of some oxygen fluorides

Kieninger, Martina; Segovia, Marc E.; Ventura, Oscar N.

doi:10.1016/s0009-2614(98)00198-5

Cited by 28 publications

(34 citation statements)

References 20 publications

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“…1,67 (6) Rotation of FOOF at the OO bond is equally as likely as dissociation into FOO and F because the corresponding barriers (cis barrier: 19.6 kcal/mol; dissociation barrier 19.5 kcal/mol) are comparable. Previous estimates as to the height of the rotational barriers of FOOF are largely exaggerated.…”

Section: Discussionmentioning

confidence: 99%

Quantum Chemical Descriptions of FOOF: The Unsolved Problem of Predicting Its Equilibrium Geometry

Kraka

2001

J. Phys. Chem. A

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Single determinant Møller-Plesset perturbation (MP) theory at second order (MP2), third order (MP3), and fourth order (MP4) with standard basis sets ranging from cc-pVDZ to cc-pVQZ quality predicts the equilibrium geometry of FOOF qualitatively incorrect. Sixth-order MP (MP6), CCSD(T), and DFT lead to a qualitatively correct FOOF equilibrium geometry r e , provided a sufficiently large basis set is used; however, even these methods do not succeed in reproducing an exact r e geometry. The latter can be achieved only by artificially increasing anomeric delocalization of electron lone pairs at the O atoms into the σ*(OF) orbitals by selectively adding diffuse basis functions, adjusting exponents of polarization functions, or enforcing an increase of electron pair correlation effects via the choice of a rigid basis set. DFT geometries of FOOF can be improved in a similar way and, then, DFT presents the best cost-efficiency compromise currently available for describing FOOF and related molecules. DFT and CCSD(T) calculations reveal that FOOF can undergo either rotation at the OO bond or dissociation into FOO and F because the corresponding barriers (trans barrier: 19.4 kcal/ mol; dissociation barrier 19.5 kcal/mol) are comparable. Previous estimates as to the height of the rotational barriers of FOOF are largely exaggerated. Rotation at the OO bond raises the barrier to dissociation because the anomeric effect is switched off. The molecular dipole moment is found to be a sensitive antenna for probing the quality of the quantum chemical description of FOOF.

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Section: Discussionmentioning

confidence: 99%

Quantum Chemical Descriptions of FOOF: The Unsolved Problem of Predicting Its Equilibrium Geometry

Kraka

2001

J. Phys. Chem. A

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“…[8][9][10][11][12][13][14][15][16][17][18] Moreover, Ventura and coworkers have successfully determined thermochemical properties of species, for which bonding patterns are difficult to describe with traditional ab initio techniques, using DFT methods. [19][20][21][22][23] For example, DFT was shown to rival or surpass CCSD(T) calculations in the study of fluorine oxides and sulfines. 24 In our laboratory, we have also demonstrated that DFT techniques can be used in the calculations of barrier heights of reactions with a first order saddle point leading to results as accurate as those obtained with conventional ab initio methods.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of reaction thermochemistry using DFT calculated molecular properties: application to trans-HONO (X¹A') à HO(X²P) + NO(X²P)

Bauerfeldt

Arbilla

Silva

2005

J. Braz. Chem. Soc.

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Cálculos B3LYP usando bases até 6-311G(3d2f,3p2d) foram utilizados para a previsão acurada de propriedades termoquímicas relacionadas à reação de dissociação trans-HONO(X 1 A') HO(X 2 P) + NO(X 2 P). Um estudo sistemático da influência da base foi realizado e resultados B3LYP foram comparados a dados experimentais e a outros resultados teóricos, calculados usando os métodos G2, G2MP2, CBS e métodos ab initio CCSD(T) e QCISD. Os resultados obtidos sugerem que para este tipo de processo unimolecular: cálculos B3LYP geram resultados mais acurados para entalpia de dissociação que outros métodos convencionais e o melhor acordo com dados experimentais foi obtido a partir de cálculos em nível B3LYP/6-311G(3d2f,3p2d): 49.2 kcal mol -1 (experimental) e 49.0 kcal mol -1 (calculado). Ainda, diferenças de entropia e de energia livre de Gibbs foram calculadas e constantes de equilíbrio foram determinadas segundo a expressão: Keq(T) = 1.16 × 10 28 × exp(-48.34/RT), para a faixa de temperatura 200 -500 K.B3LYP calculations using basis sets up to 6-311G(3d2f,3p2d) have been employed to predict accurate thermochemical properties related to the bond dissociation reaction trans-HONO(X 1 A') HO(X 2 P) + NO(X 2 P). A systematic study of the influence of the basis set was performed and results were compared with experimental data and with other calculated results, obtained using standard Gaussian methods (G2 and G2MP2), complete basis set extrapolation methods (CBS) and ab initio calculations (CCSD(T) and QCISD). The results suggest that, for this kind of unimolecular process: B3LYP calculations produce bond dissociation enthalpies that are more accurate than standard ab initio methods and) the best agreement with the experimental enthalpy has been found with B3LYP/6-311G(3d2f,3p2d) calculations: 49.2 kcal mol -1 and 49.0 kcal mol -1 , respectively. Also, entropy and Gibbs free energy have been calculated and equilibrium constants have been determined as Keq(T) = 1.16 × 10 28 × exp(-48.34/RT), for the temperature range 200 -500 K.

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“…Thus, we can have an independent theoretical assessment of Δ f H ° 298K (HSO) to compare with the ab initio results already present in the literature. We have shown previously 33–39 that density functional methods using large basis sets and isodesmic reactions can produce very accurate thermochemical results, bettering G2 and even coupled cluster singles and doubles calculations with perturbative inclusion at triple excitation [CCSD(T)] methods in many cases. We expect that the results obtained for HSO employing this methodology will be of the same quality as those obtained before.…”

Section: Introductionmentioning

confidence: 99%

Density functional investigation of atmospheric sulfur chemistry. I. Enthalpy of formation of HSO and related molecules

Denis

Ventura

2000

Int. J. Quantum Chem.

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The enthalpy of formation of several species intervening in the atmospheric chemistry of sulfur compounds (SH, H2S, SO, HSO, SOH) have been calculated using density functional theory with correlation consistent basis sets and extrapolation to the complete basis set limit. Excellent agreement with experiment is found for the species of which the enthalpy of formation are well determined. The values predicted for HSO [ΔfH°298K(HSO)=−27.8±2.1 kJ/mol] and SOH [ΔfH°298K(SOH)=−6.8±2.1 kJ/mol] agree well with previous multireference configuration interaction (MR‐CI) calculations. Based on these results, it is determined that the reaction of HSO with ozone is endothermic at all temperatures but spontaneous above 220 K because of entropic effects. Both the reactions of dissociation SOH→H+SO and isomerization HSO→SOH are studied in detail, and the transition states located. The results are also in agreement with the much more costly MR‐CI results. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 80: 439–453, 2000

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A discrepancy between experimental and theoretical thermochemical characterization of some oxygen fluorides

Cited by 28 publications

References 20 publications

Quantum Chemical Descriptions of FOOF: The Unsolved Problem of Predicting Its Equilibrium Geometry

Quantum Chemical Descriptions of FOOF: The Unsolved Problem of Predicting Its Equilibrium Geometry

Evaluation of reaction thermochemistry using DFT calculated molecular properties: application to trans-HONO (X¹A') à HO(X²P) + NO(X²P)

Density functional investigation of atmospheric sulfur chemistry. I. Enthalpy of formation of HSO and related molecules

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