Theoretical study on electronic structures of oxygenated dipoles and mechanisms of ozonolysis reactions

Yoshioka, Yasunori; Yamaki, Daisuke; Kubo, Shigehiro; Nishino, Masamichi; Yamaguchi, Kizashi; Mizuno, Kazuhiko; Saito, Isao

doi:10.1002/ejtc.52

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…To model a rational series of oxidized systems that may occur during the O 3 pulse, we investigate the reactions that can occur between surface A and successive singlet O atoms. Such O atoms may come from the thermal or photolytic dissociation of O 3 or O 2 or from an oxygen plasma, but there are well-known deficiencies in the DFT treatment of these molecules, , so we use singlet O( 1 D) as the reference reactant throughout. In any case, we base our arguments on the relative energies of products, which are unaffected by the choice of reactant.…”

Section: Computationalmentioning

confidence: 99%

Ozone-Based Atomic Layer Deposition of Alumina from TMA: Growth, Morphology, and Reaction Mechanism

Elliott¹,

Scarel²,

Wiemer³

et al. 2006

Chem. Mater.

177

195

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We examine the effect of growth temperature in the 150−300 °C range on the structural and morphological properties of Al2O3 films deposited using atomic layer deposition, contrasting the effect of H2O and O3 as oxygen sources. Trimethylaluminum (TMA) is the metal source. A mechanism for the O3 reaction is investigated using ab initio calculations and provides an explanation for the observed temperature dependence. The simulations show that hydroxyl groups are produced at the surface by the oxidation of adsorbed methyl groups by O3. This is confirmed by the measured rates; both H2O and O3 processes show molar growth rates per cycle that decrease with increasing reactor temperature, consistent with a decrease in hydroxyl coverage. At no temperature does the O3 process deposit more Al2O3 per cycle than the H2O process. Morphological characterization shows that O3 as the oxygen source yields lower-quality films than H2O; the films are less dense and rougher, especially at low growth temperatures. The existence of voids correlates with the low film electronic density. This may indicate the low mobility of surface hydroxyl at low temperatures, an effect that is washed out by repeated exchange with the vapor phase in the H2O case.

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Section: Computationalmentioning

confidence: 99%

Ozone-Based Atomic Layer Deposition of Alumina from TMA: Growth, Morphology, and Reaction Mechanism

Elliott¹,

Scarel²,

Wiemer³

et al. 2006

Chem. Mater.

177

195

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“…Interaction energies (∆E, eV) between the "frontier" molecular orbitals of nitrilimine and ethene (lowest interaction energies are in boldface type). majority of 1,3-dipolar cycloaddition reactions are believed to proceed via a concerted mechanism (23), although there are now several reports of reactions with a biradical mechanism (1,(61)(62)(63)(64)(65).…”

Section: The Nitrilimine Cycloaddition Mechanismmentioning

confidence: 99%

A computational study of the 1,3-dipolar cycloaddition reaction mechanism for nitrilimines

Mawhinney¹,

Muchall²,

Peslherbe³

2005

Can. J. Chem.

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The [3+2] and [1+2] cycloaddition pathways between ethene and a series of 13 nitrilimines (R1CNNR2) have been examined by density functional theory [PBE0/6-311++G(2df,pd)] calculations. All reactions have low barriers ranging from 14.14 (R1 = CH3, R2 = H) to 1.01 (R1 = R2 = F) kcal mol1, and large reaction exothermicities consistent with the transient nature of nitrilimines. The [3+2] and [1+2] transition-state structures are very similar, mainly differing in the relative orientation of their fragments and the newly forming CC bond distance, and exhibit only minor deviations from the structures of the reactants. Both reaction pathways are concerted and asynchronous, but the [1+2] reaction has a greater degree of asynchronicity. Examination of the frontier molecular orbitals reveals that both the [3+2] and [1+2] barrier heights are related to two sets of orbital interactions, with the interaction between the lowest unoccupied molecular orbital π [Formula: see text] of nitrilimine and the highest occupied molecular orbital of ethene in common. The second interaction in both cases is carbene-like. A relationship between the weights of the 1,3-dipolar resonance contribution in the various nitrilimines and the corresponding [3+2] barrier heights was not found, but a good correlation could be found between the [1+2] barrier heights and both the 1,3-dipolar and carbene contributions. Inspection of the potential energy surface in the vicinity of the two transition states for the reaction between unsubstituted nitrilimine and ethene suggests that the observed [3+2] product is a result of an initial carbene-like approach of the two fragments followed by a ridge bifurcation that leads to the [3+2] product minimum. Key words: nitrilimines, 1,3-dipole, carbene, [3+2] cycloaddition, [1+2] cycloaddition, density functional theory (DFT).

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“…[41][42][43] The significant diradical character of 1,3-dipoles lead to a vigorous debate of concerted versus stepwise mechanisms for 1,3-dipolar cycloadditions. [44][45][46] Early ab initio studies by Goddard, 47 Hiberty, 48 Houk, 49 and others [50][51][52][53] showed that ozone and its concerted TS have a triplet instability at the RHF and MP2 levels of theory. Unrestricted Hartree-Fock theory predicts a stepwise pathway to be favored over the concerted pathway, whereas second-order unrestricted Møller-Plesset perturbation theory (UMP2) computations favor the concerted cycloaddition, with a barrier around 10 kcal mol -1 .…”

Section: Introductionmentioning

confidence: 99%

“…Ozone has a zwitterionic (dipole) all-octet resonance structure and cycloadds at the 1,3 termini with alkenes and alkynes. − Typically represented by closed-shell zwitterionic structures, natural orbital occupation and generalized valence bond computations estimate diradical character of ozone to be nearly 33%. − The significant diradical character of 1,3-dipoles lead to a vigorous debate of concerted versus stepwise mechanisms for 1,3-dipolar cycloadditions. − Early ab initio studies by Goddard, Hiberty, Houk, and others − showed that ozone and its concerted TS have a triplet instability at the RHF and MP2 levels of theory. Unrestricted Hartree−Fock theory predicts a stepwise pathway to be favored over the concerted pathway, whereas second-order unrestricted Møller−Plesset perturbation theory (UMP2) computations favor the concerted cycloaddition, with a barrier around 10 kcal mol -1 .…”

Section: Introductionmentioning

confidence: 99%

Thinking Out of the Black Box: Accurate Barrier Heights of 1,3-Dipolar Cycloadditions of Ozone with Acetylene and Ethylene

2008

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Accurate barriers for the 1,3-dipolar cycloadditions of ozone with acetylene and ethylene have been determined via the systematic extrapolation of ab initio energies within the focal point approach of Allen and co-workers. Electron correlation has been accounted for primarily via coupled cluster theory, including single, double, and triple excitations, as well as a perturbative treatment of connected quadruple excitations [CCSD, CCSD(T), CCSDT, and CCSDT(Q)]. For the concerted [4 + 2] cycloadditions, the final recommended barriers are DeltaH(0K) = 9.4 +/- 0.2 and 5.3 +/- 0.2 kcal mol(-1) for ozone adding to acetylene and ethylene, respectively. These agree with recent results of Cremer et al. and Anglada et al., respectively. The reaction energy for O3 + C2H2 exhibits a protracted convergence with respect to inclusion of electron correlation, with the CCSDT/cc-pVDZ and CCSDT(Q)/cc-pVDZ values differing by 2.3 kcal mol-1. Recommended enthalpies of formation (298 K) for cycloadducts 1,2,3-trioxole and 1,2,3-trioxolane are +32.8 and -1.6 kcal mol(-1), respectively. Popular composite ab initio approaches [CBS-QB3, CBS-APNO, G3, G3B3, G3(MP2)B3, G4, G4(MP3), and G4(MP2)] predict a range of barrier heights for these systems. The CBS-QB3 computed barrier for ozone and acetylene, DeltaH(0K) = 4.4 kcal mol(-1), deviates by 5 kcal mol(-1) from the focal point value. CBS-QB3 similarly underestimates the barrier for the reaction of ozone and ethylene, yielding a prediction of only 0.7 kcal mol(-1). The errors in the CBS-QB3 results are significantly larger than mean errors observed in application to the G2 test set. The problem is traced to the nontransferability of MP2 basis set effects in the case of these reaction barriers. The recently published G4 and G4(MP2) approaches perform substantially better for O3 + C2H2, predicting enthalpy barriers of 9.0 and 8.4 kcal mol(-1), respectively. For the prediction of these reaction barriers, the additive corrections applied in the majority of the composite approaches considered lead to worse agreement with the reference focal point values than would be obtained relying only on single point energies evaluated at the highest level of theory utilized within each composite method.

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Theoretical study on electronic structures of oxygenated dipoles and mechanisms of ozonolysis reactions

Cited by 4 publications

References 23 publications

Ozone-Based Atomic Layer Deposition of Alumina from TMA: Growth, Morphology, and Reaction Mechanism

Ozone-Based Atomic Layer Deposition of Alumina from TMA: Growth, Morphology, and Reaction Mechanism

A computational study of the 1,3-dipolar cycloaddition reaction mechanism for nitrilimines

Thinking Out of the Black Box: Accurate Barrier Heights of 1,3-Dipolar Cycloadditions of Ozone with Acetylene and Ethylene

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