An Effective Hamiltonian Molecular Orbital-Valence Bond (MOVB) Approach for Chemical Reactions as Applied to the Nucleophilic Substitution Reaction of Hydrosulfide Ion and Chloromethane

Song, Lingchun; Mo, Yirong; Gao, Jiali

doi:10.1021/ct800421y

Cited by 22 publications

(64 citation statements)

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“…In addition, the relative energies calculated between reactants, ion-dipole complexes and products are given in Table VI. One can see that the calculated values agree with the reported results [14]. At the same time, the present work retains the shape of the pathway, which is in accordance with the studies reported in the literature [14], which illustrates deeply that the AIM method is conformable to the nucleophilic substitution reaction of hydrosulfide ion and halomethane.…”

Section: Reaction Pathway For the Hschsupporting

confidence: 92%

“…One can see that the calculated values agree with the reported results [14]. At the same time, the present work retains the shape of the pathway, which is in accordance with the studies reported in the literature [14], which illustrates deeply that the AIM method is conformable to the nucleophilic substitution reaction of hydrosulfide ion and halomethane. The structures of the most relevant stationary points are fully optimized with MP2/cc-pVDZ level of theory and are given in Figure 2.…”

Section: Reaction Pathway For the Hschsupporting

confidence: 92%

“…Two potential energy minima, which are separated by a central energy barrier corresponding to the [XACH3AY] À (where X and Y are halogen atoms) transition state, correspond to the formation of ion molecule intermediates on both the reactant and product sides of the reaction. Recently, Song and co-workers examined the nucleophilic substitution reaction of hydrosulfide ion with chloromethane by using Effective Hamiltonian molecular orbital-valence bond approach [14]. Their results proved the reaction mechanism of hydrosulfide ion with chloromethane preliminary.…”

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confidence: 95%

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Theoretical study on the mechanisms of the nucleophilic substitution reactions of hydrosulfide ion and halomethanes

Long

Jing

et al. 2010

Int J of Quantum Chemistry

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Three species involved in the nucleophilic substitution reaction of hydrosulfide ion and halomethanes are investigated by ab initio calculations. Geometries for stationary structures along the reaction paths are fully performed with the second-order Møller-Plesset perturbation approximation with the cc-pVDZ basis set. The monomer geometries determined by the MP2 method match the experimental results very well. Single point energy calculations are carried out at the coupled cluster with perturbative triple excitations CCSD (T) theory with aug-cc-pVDZ basis set. Halomethanes have three conformers here, which lead to the three product channels,, and HSCH 3 þ Br À1 . The investigation encompasses the six complexes formed among three channels, respectively. By selecting the six complexes as the model, we investigate the binding energy, topological property of the electron charge density and their Laplacian in detail theoretically. Electrostatic density potential maps of halomethanes are generated for the determination of attractive interaction sites. It is proved that the similar misshaped electron clouds of the three halogen atoms result in the similar properties of the carbon-halogen bonds, and reveals that the product ion-dipole complexes interactions are predominantly electrostatic in nature. The calculated results predict the binding energy of the most stable complex in six complexes is À47.06 kcal/mol at the MP2 level of theory. The second channel has the lowest energy barrier, which is À3.63 kcal/mol at the CCSD (T) levels of theory, is expected to be the most important pathway. It occurs via CACl cleavage accompanied by CAS bond formation. The other two channels have higher energy barriers and are expected to have smaller rates.

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Section: Reaction Pathway For the Hschsupporting

confidence: 92%

Section: Reaction Pathway For the Hschsupporting

confidence: 92%

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confidence: 95%

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Theoretical study on the mechanisms of the nucleophilic substitution reactions of hydrosulfide ion and halomethanes

Long

Jing

et al. 2010

Int J of Quantum Chemistry

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“…The MOVB method was developed to provide a computationally efficient procedure to study these effects as well as chemical reactions in solution and in enzymes 3,13–16,52. In this section, we present an approach to use BLDFT to evaluate the matrix elements of VB Hamiltonians.…”

Section: Methodsmentioning

confidence: 99%

“…In this case, the dependence on overlap is implicit. However, the effect of solvation on V 12 may not be adequately assessed using eq 6 if the diabatic PES ( H 11 and H 22 ) and the adiabatic ground-state energy are not determined consistently with the same basis and theory or by optimizing both the orbital and configuration coefficients simultaneously 3,13–16…”

Section: Introductionmentioning

confidence: 99%

Block-Localized Density Functional Theory (BLDFT), Diabatic Coupling, and Their Use in Valence Bond Theory for Representing Reactive Potential Energy Surfaces

Cembran

Song

et al. 2009

J. Chem. Theory Comput.

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126

345

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A multistate density functional theory in the framework of the valence bond model is described. The method is based on a block-localized density functional theory (BLDFT) for the construction of valence-bond-like diabatic electronic states and is suitable for the study of electron transfer reactions and for the representation of reactive potential energy surfaces. The method is equivalent to a valence bond theory with the treatment of the localized configurations by using density functional theory (VBDFT). In VBDFT, the electron densities and energies of the valence bond states are determined by BLDFT. A functional estimate of the off-diagonal matrix elements of the VB Hamiltonian is proposed, making use of the overlap integral between Kohn-Sham determinants and the exchangecorrelation functional for the ground state substituted with the transition (exchange) density. In addition, we describe an approximate approach, in which the off-diagonal matrix element is computed by wave function theory using block-localized Kohn-Sham orbitals. The key feature is that the electron density of the adiabatic ground state is not directly computed nor used to obtain the ground-state energy; the energy is determined by diagonalization of the multistate valence bond Hamiltonian. This represents a departure from the standard single-determinant Kohn-Sham density functional theory. The multistate VBDFT method is illustrated by the bond dissociation of and a set of three nucleophilic substitution reactions in the DBH24 database. In the dissociation of , the VBDFT method yields the correct asymptotic behavior as the two protons stretch to infinity, whereas approximate functionals fail badly. For the S N 2 nucleophilic substitution reactions, the hybrid functional B3LYP severely underestimates the barrier heights, while the approximate two-state VBDFT method overcomes the self-interaction error, and overestimates the barrier heights. Inclusion of the ionic state in a three-state model, VBDFT(3), significantly improves the computed barrier heights, which are found to be in accord with accurate results. The BLDFT method is a versatile theory that can be used to analyze conventional DFT results to gain insight into chemical bonding properties, and it is illustrated by examining the intricate energy contributions to the ion-dipole complex stabilization.

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Valence Bond‐Based Hybrid Quantum Mechanics Molecular Mechanics Approaches and Proper Inclusion of the Effect of the Surroundings

Shurki

Sharir-Ivry

2014

Israel Journal of Chemistry

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The pioneering development of multiscale models for complex chemical systems by Karplus, Levitt, and Warshel, including the hybrid quantum mechanics molecular mechanics (QM/MM) approach and its application to enzymes, established a new field in chemistry that allows the modeling of reactivity within complex chemical systems. Inspired by the potential of such methods, many groups developed different QM/MM variants. Valence bond (VB) theory, which always was and still is an important conceptual tool for chemists, is well suited to deal with problems of chemical reactivity. Hence, here we review VB‐based QM/MM methods, including the early semi‐empirical methods that utilize VB concepts and more recent ab initio VB‐based QM/MM methods. Special emphasis is given to the different ways to include effects of the surroundings on the solute. It is shown that within the VB framework, simple mechanical embedding for each diabatic state, followed by mixing of the states, accounts for most of these effects.

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An Effective Hamiltonian Molecular Orbital-Valence Bond (MOVB) Approach for Chemical Reactions as Applied to the Nucleophilic Substitution Reaction of Hydrosulfide Ion and Chloromethane

Cited by 22 publications

References 65 publications

Theoretical study on the mechanisms of the nucleophilic substitution reactions of hydrosulfide ion and halomethanes

Theoretical study on the mechanisms of the nucleophilic substitution reactions of hydrosulfide ion and halomethanes

Block-Localized Density Functional Theory (BLDFT), Diabatic Coupling, and Their Use in Valence Bond Theory for Representing Reactive Potential Energy Surfaces

Valence Bond‐Based Hybrid Quantum Mechanics Molecular Mechanics Approaches and Proper Inclusion of the Effect of the Surroundings

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