Proceedings - Interdisciplinary Center for Nanotoxicity

More documents

Recommendations

Info

120 Conference on Current Trends in Computational Chemistry 2009 O2, the contribution of entropy to the free energy of desorption is T S =10.8 kcal/mol at 298 K. The calculated activation energies at MP2/6‐31+G(d) level for N2O dissociation on Al‐ZSM‐5 and AlO‐ZSM‐5 are 13.90 and 26.87 kcal/mol at 298 K, respectively. The calculated activation energy at MP2/6‐31+G(d) level for N2O dissociation on AlO2‐ZSM‐5 is 38.25 kcal/mol. The calculated energy of the singlet oxygen desorption from 3T ‐ [AlO3] + cluster H (298 K)=+46.4 kcal/mol at MP2/6‐31+G(d) level is significantly higher than the barriers of oxidation reactions. When one takes into account the entropy gained upon desorption of singlet O2, the contribution of entropy to the free energy of desorption is T S =11.0 kcal/mol at 298 K. Thus, the method B3LYP seriously underestimates the activation energy for N2O dissociation on Al/AlO/AlO2‐ZSM‐ 5. The problem here, of course, is that current functionals do not correctly describe the dispersion energy, which is well described by MP2 calculations. Therefore, further DFT investigations are needed that are validated by comparison to available experimental data or high‐level quantum chemistry methods that treat electron correlation more accurately. 1. Solkan, V. N.; Zhidomirov, G. M.; Kazansky, V. B. Int. J. Quantum Chem. 2007, Vol. 107, Iss. 13. pp 2417‐2425.
Conference on Current Trends in Computational Chemistry 2009 A New Insight into Mechanism of Formation of Peroxyl Radical in Anhydrous Acids: Post‐Hartree‐Fock MP2 Study Vitaly Solkan N. D. Zelinski Institute of Organic Chemistry, RAS, 119991 Moscow, Leninskii pr. 47, Russian Federation; Email: solkanvn@ioc.ac.ru Quantum mechanics calculations at MP2/6‐311++G(d, p) level were utilized to study the process of activation of a dioxygen in strong acids, namely, FSO3H and CF3COOH. We have designed donor/acceptor model systems with well‐defined electron transfer distances and proton hydrogen bond geometries. We concentrated on the situation where the electron and proton have different sources within a reaction complex, as indicated below (CF3CO2(‐ )…O2(T)…H2O2CCF3(+)) or (FSO3(‐)…O2(T) H2O3SF(+)). In this complex protonated acid molecule can react with a dioxygen to give the HOO radical in case if an electron transfers from the anion. This reaction could occur by (i) initial proton transfer (PT) to form OOH(+) followed by electron transfer (ET), (ii) ET to form superoxide anion‐radical followed by PT, or (iii) proton‐ coupled electron transfer (PCET) with no intermediates. Theoretical calculations have revealed that the reaction of dioxygen with protonated acid occurs via a single pathway by a mechanism that has proton‐coupled electron transfer character. In this reaction, the mechanism can be partially described as a process in which the O‐H hydrogen from FSO3H2(+) or CF3CO2H2(+) is transferred as a proton to dioxygen with the accompanying electron coming from the electron system of the anion FSO3(‐) or CF3CO2(‐), respectively. Thus, the anionic species of the complex participate only as electron‐transfer partners. A major goal of our current research is to monitor the fate of the proton in response to the electron and vice versa. The changes in the geometrical parameters, charge, and spin densities distribution along the reaction coordinate are discussed. Some relationships between the amount of transferred electron density and the changes in geometrical parameters and energies are given. The peculiarities of potential energy surfaces of complex (CF3CO2(‐)…O2(T)…H2O2CCF3(+)) in the ground and excited electronic states were also investigated by means of DFT/B3LYP method with 6‐311++G(d, p) basis set. Theoretical results obtained employing density functional theory well agrees with data obtained by MP2 method. Many fundamental small‐molecule transformations in nature require the coupled transport of both proton and electron equivalents to affect bond‐making and bond‐breaking catalysis. Quantum mechanics calculations at MP2/6‐311++G(d, p) level were utilized to study the process of activation of a dioxygen in HF with the assistance of the appropriate alkenes. We concentrated on the situation where the electron and proton have different sources within a reaction complex, as indicated below (Me2C=CMe2…O2(T)…HFH(+)…HF). In this complex protonated acid molecule can react with a dioxygen to give the HOO radical in case if an electron transfers from the Me2C=CMe2 molecule. Theoretical calculations have revealed that the reaction of dioxygen with protonated acid occurs via a single pathway by a mechanism that has proton‐coupled electron transfer character. In this reaction, the mechanism can be partially described as a process in which the hydrogen from HFH(+) is transferred as a proton to dioxygen with the accompanying electron coming from the electron system of the Me2C=CMe2 molecule which converted to cation‐radical. The changes in the geometrical parameters, charge, and spin densities distribution along the reaction coordinate are discussed. The 121
Page 2:
Organizing Committee Shonda Allen-H
Page 6 and 7:
Schedule of Events Conference on Cu
Page 8:
Table of Contents Conference on Cur
Page 11 and 12:
12 Conference on Current Trends in
Page 13 and 14:
Page 15 and 16:
Page 18 and 19:
Page 20 and 21:
Page 22 and 23:
22 Figure 1. The structure of artif
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41:
Page 42 and 43:
Page 44 and 45:
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
66 : au : au Conference on Curren
Page 68 and 69:
68 Ag 36 (D 3d) Ag 42 (D 3) Ag 48 (
Page 70 and 71: 70 Conference on Current Trends in
Page 76 and 77: 76 Table 2. Calculated scale factor
Page 86 and 87: 86 Isodesmic Model Conference on Cu
Page 148: List of Participants Conference on
Page 161 and 162: Author Index Conference on Current
show all

Proceedings - Interdisciplinary Center for Nanotoxicity

Create successful ePaper yourself

Delete template?

Save as template?