Theoretical analysis of proton transfers in symmetric and asymmetric systems

Cao, H. Z.; Allavena, M.; Tapia, O.; Evleth, E. M.

doi:10.1021/j100255a009

Cited by 62 publications

(34 citation statements)

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“…The gas phase experimental geometry is used for the water molecule31 and an optimized geometry for the oxonium ion. 34 The water-water interaction is computed with the MCY potential,32 as described in an early paper,33 and the ion-water Many other theoretical studies, with variable accuracy, appeared in the literature.5,9-14,16-24,27-29 Precise quantum mechanical determinations became feasible only in the later 1 980s21-24328 due to the spectacular development of computer facilities, which offered new possibilities to theoreticians. Among them, Monte Carlo or molecular dynamics calculations, together with the use of a continuum model in ab initio calculations, have favored the emergence of new analytical potentials.…”

Section: Methodsmentioning

confidence: 99%

Theoretical Studies of H+(H2O)5

Corongiu¹,

Kelterbaum²,

Kochanski³

1995

J. Phys. Chem.

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Calculations have been performed on 10 structures of the cluster H+(H20)5. It is shown that the most stable ones are an open (Eigen) and a cyclic four-membered-ring structure very close in energy and possibly degenerate. This can explain that different structures were proposed by experimentalists. The easy evolution of some structures into others is likely related to the nature of the first solvation shell in larger clusters or solutions. Vibrational frequencies, useful to interpret experimental data, are computed for the two most stable structures. The Problem: Structure of H+(HzO)s and the First Solvation ShellIn 1954, Eigen et al.' proposed as a hydration model for the proton in aqueous solution and ice an oxonium ion H30+ surrounded by three water molecules in a first solvation shell. In some early theoretical work (1956) the presence of a fourth water molecule in the first solvation shell has also been suggested;* three water molecules are hydrogen bonded with the three hydrogen atoms of the ion, while the fourth water molecule is located above the oxygen atom (Figure 1, protondonor structure 1). Since then, there were many proposal^^-^^ on the structure and coordination number, and presently the issue is not settled, neither theoretically nor experimentally. Some of these studies are concemed with the cluster H30+(H20)4, others with larger systems.The first attempt by Newton et aL3 in 1971 to study such systems with ab initio quantum mechanical calculations was restricted to small hydrates involving, at best, four water molecules and the oxonium ion. Using a 4-31G basis set at the Hartree-Fock level, the authors optimized a few structures for the system &O+(H*0)3 and then added to it a fourth molecule. Within these limitations the most stable structure has three water molecules in the Eigen-like structure first shell and a fourth water molecule in the second shell, hydrogen bonded to one water molecule of the first shell with an 0. * 0 distance arbitrarily chosen (Figure 1, structure 2). The interpretation of an infrared spectrum published some time later is based on such a structure.8 However, two experimental paper^^.^ suggested that the fist solvation shell has four water molecules. In particular, from X-ray and thermal neutron studies of hydrochloric acid solutions at 20 "C, Triolo et a1.6 proposed a charge-dipole complex (Figure 1, structure 3). In a further work, ' Newton (1977) extended his studies to structures 1 and 3 in order to check this assumption. He found that neither of these two structures were stabilized with respect to H30+(H20)3 f Hz0, with a more favorable situation for the charge-dipole complex structure 3 than for the hydrogen bonded structure 1. A complete optimization of these structures with ab initio calculations was unfortunately not possible at the time, and the true minima might have been missed. Furthermore, it must be pointed out that the structure of the first shell may be different 'Abstract published in Advance ACS Abstracts, April 15, 1995.

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Section: Methodsmentioning

confidence: 99%

Theoretical Studies of H+(H2O)5

Corongiu¹,

Kelterbaum²,

Kochanski³

1995

J. Phys. Chem.

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“…The protocol introduced to help calculate TS structures has been invaluable in this respect. 13 The important results 40 as far as the present work is concerned are: (1) the saddle point character of the complexes has been retained; (2) the coordinates controlling the downhill displacement still are the ones found for the simple model used in the present work; (3) remarkable similarities in the solvation pattern involving the C 2 center are also found.…”

Section: Discussionmentioning

confidence: 74%

“…Tapia ,8-unsaturated carbonyl compound. 16,17 This organic reaction l6 presents some features which adapt well to solvation studies: (1) The mechanism is solvent dependent; (2) the reaction pathways for aqueous and nonaqueous acid media differ completely; (3) in aqueous medium the solvent participates directly in the reaction pathway of the rate limiting step (rls); (4) in aqueous acid media two reactive channels are available; (5) moreover, for the rls the species undergoing the rearrangement is a cation all along the reaction pathway, Solvent effects are therefore expected to be significant.…”

Section: Introductionmentioning

confidence: 96%

Solvent effects on chemical reaction profiles. I. Monte Carlo simulation of hydration effects on quantum chemically calculated stationary structures

Tapia

Lluch

1985

The Journal of Chemical Physics

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Metropolis Monte Carlo simulations of hydration effects on rigid solutes characterizing the reactant, transition state (TS), and product for the rate limiting step of an acid catalized rearrangement of an a-acetylenic alcohol to α, β-unsaturated carbonyl compounds are calculated. The model compound corresponds to the protonated 3 methyl-but-1-yne-3-o1. The electronic structure and geometry of the corresponding species are determined with ab initio analytical gradient techniques; a 4-31G basis set has been used. Electrostatic and solute shape effects on samples having 125 MCY–water molecules at 300 K have been examined. Gurney’s model for ion–molecule interactions has been adopted. Although the solute–water potential used is very simple, the results on hydration energetics appear to be fairly reasonable. Solute shapes are found to play a significant role in producing differential solvation effects. Electrostrictive effects have been made evident by running MC simulations with fully uncharged solutes. A solvent activation barrier is detected. From the study of the TS solvation structures a possible incidence of ionic strength, counterion presence, and structure-making or breaking solutes can be conjectured. The structural features found for the solvation sheaths of reactant, TS, and product are in excellent agreement with the postulated molecular mechanism.

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“…Geometry of hydroxonium ion clusters with several (up to 10) water molecules in gas and condensed phase has been studied in detail as well [20][21][22][23][24][25][26][27][28][29][30]. However, selectivity of the intermolecular bonding involving hydroxonium ion and its effect on the cluster nuclearity have remained the open issues so far.…”

mentioning

confidence: 99%

“…Vibrational and electronic spectra were simulated using the B3LYP functional and the 6-311G** basis allowing the best coincidence between the experimental and the simulated О-Н dissociation energy and geometry parameters of Н 2 О molecule [18,[25][26][27][28]. On top of that, the B3LYP and B3PW91 functionals could adequately reproduce vibrational frequencies of the H 3 O + ion and its clusters with water molecules [15,16,23,[31][32][33][34][35].…”

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confidence: 99%

Peculiarities of formation of hydroxonium ion and its small clusters

Kobzev

Zaika

2015

Russ J Gen Chem

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Density functional theory combined with the restricted open-shell Hartree-Fock method using the B3LYP, BLYP, and B3PW91 exchange-correlation functionals in the 6-311G** basis has been applied to determine equilibrium geometry of water-containing clusters 1 (H 3 O + -nH 2 O) with n = 1-3, 5, 6 and 1 (H 3 O + -3H 2 O)Cl -. The SA-MCSCF simulation has revealed a series of electronic terms of hydroxonium ion and energy profiles of its formation. Energy profiles of H 3 O + interaction with H 2 O have been simulated and analyzed. Vibrational spectra have been simulated for all the mentioned complexes in the equilibrium state, and regularities of changes of the fundamental vibrational frequencies with the increasing nuclearity of the complexes have been discovered.

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Theoretical analysis of proton transfers in symmetric and asymmetric systems

Cited by 62 publications

References 1 publication

Theoretical Studies of H+(H2O)5

Theoretical Studies of H+(H2O)5

Solvent effects on chemical reaction profiles. I. Monte Carlo simulation of hydration effects on quantum chemically calculated stationary structures

Peculiarities of formation of hydroxonium ion and its small clusters

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