International Journal of Quantum Chemistry

Cover image for Vol. 112 Issue 22

Special Issue: Mexican Theoretical Physical Chemistry Meetings

15 November 2012

Volume 112, Issue 22

Pages i–iv, 3559–3660

Issue edited by: J. Raúl Álvarez-Idaboy, Marcelo Galván, Alberto Vela, Claudio M. Zicovich-Wilson

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Full Papers
    1. You have free access to this content
      Cover Image, Volume 112, Issue 22 (pages i–ii)

      Version of Record online: 16 OCT 2012 | DOI: 10.1002/qua.24342

      Thumbnail image of graphical abstract

      Aztec symbolism and quantum mechanical concepts are mixed to celebrate the Mexican Theoretical Physical Chemistry Meetings (RMFQT). The four bicephalous snakes are an allegory of the importance of symmetry in quantum systems, depicting the S4 group. The four pictographs just below it depict the five irreducible representations of that group in which the number of flowers corresponds to the dimensions of the representation. The snakes on both sides represent the creation and annihilation operators of the second quantization formalism. The two red circles and the glyph in the upper left corner indicate that this is part two of this special issue and the year 2012 of publication. A more detailed cover description by the artist, Renato Lemus, a theoretical chemist at the Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, can be found at the RMFQT site: http://rmfqt.cinvestav.mx.

    2. You have free access to this content
      Inside Cover, Volume 112, Issue 22 (pages iii–iv)

      Version of Record online: 16 OCT 2012 | DOI: 10.1002/qua.24343

      Thumbnail image of graphical abstract

      The stable structure of small neutral and singly charged silver bromide clusters is still a subject of debate. In the case of the AgBr2 and AgBrmath image molecules several theoretical approaches yield the same results, while there is no consensus over the ground state structure of the neutral AgBr2 cluster. Using complete active space self-consistent field (CASSCF) and multireference second order perturbation theory, A. Ramírez-Solís reports on page 3559 a new, linear centrosymmetric structure AgBr2 cluster, in disagreement with previous theoretical work. This discrepancy highlights the crucial role played by the quality of the valence atomic basis sets in the calculations of this type of transition metal complex.

  2. Full Papers

    1. Top of page
    2. Cover Image
    3. Full Papers
    1. The molecular structure of AgBr2 and AgBr2+. A benchmark CASSCF, CASPT2, and averaged coupled pair functional study (pages 3559–3563)

      A. Ramírez-Solís

      Version of Record online: 15 MAY 2012 | DOI: 10.1002/qua.24167

      Thumbnail image of graphical abstract

      The stable structure of small neutral and singly charged silver bromide clusters is still debated in literature. Variational and perturbational multireference calculations using large optimized valence basis sets confirms the previously predicted structure for AgBr2+, while for the neutral AgBr2 a linear centrosymmetric structure is found, in disagreement with previous theoretical work. This discrepancy highlights the crucial role played by the quality of the valence atomic basis sets for this type of transition metal molecules.

    2. Stability and bonding in the borane–H2 complexes (pages 3564–3569)

      Mariano Méndez and Andrés Cedillo

      Version of Record online: 4 JUN 2012 | DOI: 10.1002/qua.24188

      Thumbnail image of graphical abstract

      Borane–H2 complexes, as BH3–H2, have been proposed as intermediates of the hydrolysis reaction of the tetrahydroborate anion to produce molecular hydrogen and boric acid. The gas-phase stability of such complexes is explored in this work by several quantum chemical methods, including MP2 and DFT, and local reactivity parameters from the acceptor Fukui function. Highly correlated methods are found to be necessary for an accurate description of the energetics of these systems.

    3. Relationship between local reactivity indices and the hammett constant for isatoic anhydride and its derivatives (pages 3570–3577)

      José S. Durand-Niconoff, Luis Cruz-Kuri, Jesús S. Cruz-Sánchez, Myrna H. Matus and Fernando R. Ramos-Morales

      Version of Record online: 5 JUN 2012 | DOI: 10.1002/qua.24195

      Thumbnail image of graphical abstract

      Reactivity indices are used as descriptors of changes in the reactivity pattern of a molecule resulting from substitutions of functional groups. Indices such as local softness, condensed Fukui function, relative electrophilicity, and relative nucleophilicity are used in this work to study the local reactivity of isatoic anhydride and its derivates. A statistical linear model is proposed to describe the relationship between substituent effect and gas phase reactivity indices with respect to Hammett constant values.

    4. Concurrent phenomena at the transition region of selected elementary chemical reactions: An information-theoretical complexity analysis (pages 3578–3586)

      Rodolfo O. Esquivel, Moyocoyani Molina-Espíritu, Jesús S. Dehesa, Juan Carlos Angulo and Juan Antolín

      Version of Record online: 8 JUN 2012 | DOI: 10.1002/qua.24219

      Thumbnail image of graphical abstract

      Information-theoretic measures can provide simple pictorial chemical descriptions of atoms and molecules. In the case of the simplest hydrogen abstraction and exchange reaction, the information-theoretic complexity analysis of the one-particle density, performed in position and momentum spaces, predicts all the chemically significant aspects associated with the reaction, i.e., reactant/product, bond cleavage energy, bond breaking/forming, accumulation/releasing energy, and the transition state regions.

    5. Density-functional-theory study of α-cyclodextrin inclusion complexes (pages 3587–3593)

      Hilda Santillán-Vargas, José-Zeferino Ramírez, Jorge Garza and Rubicelia Vargas

      Version of Record online: 12 JUL 2012 | DOI: 10.1002/qua.24225

      Thumbnail image of graphical abstract

      Using the density functional theory it is shown how the electrostatic potential generated by a-cyclodextrin governs the behavior of its complexes. Some of these results are found to be in disagreement with those computed in precedence using semiempirical and the B3LYP//PM3 method.

    6. The reduced density gradient in atoms (pages 3594–3598)

      Jorge M. del Campo, José L. Gázquez, Rodrigo J. Alvarez-Mendez and Alberto Vela

      Version of Record online: 26 JUN 2012 | DOI: 10.1002/qua.24241

      Thumbnail image of graphical abstract

      The reduced density gradient is a very important variable in the development of approximate exchange energy functionals, particularly in the case of the generalized gradient approximation. This work presents an analysis of this quantity in atoms from Li to Xe, to get a better understanding of its behavior.

    7. Reaction mechanism of hydrogenation and direct desulfurization routes of dibenzothiophene-like compounds: A density functional theory study (pages 3599–3605)

      Diego Valencia, Laura Peña and Isidoro García-Cruz

      Version of Record online: 22 JUN 2012 | DOI: 10.1002/qua.24242

      Thumbnail image of graphical abstract

      Sulfur elimination from fuel is a crucial technological challenge rising by current environmental regulations. The reaction routes of hydrogenation and direct desulfurization processes involving dibenzothiophenes-derivates are compared by means of density functional theory simulations. The hydrogenation routes is found to have lower activation and better energetics than direct desulfurization.

    8. Hydrogen site occupation and electronic structure in the La2Ni2In intermetallic and hydrides (pages 3606–3611)

      Andrea Aburto and Emilio Orgaz

      Version of Record online: 19 JUN 2012 | DOI: 10.1002/qua.24243

      Thumbnail image of graphical abstract

      This study reports on a series of intermetallic compounds R2Ni2In (R = La, Ce, Pr, Nd) with good agreement between computed structural properties and experimental data. Hydrogen occupation in the intermetallic compounds can be rationalized in terms of the local coordination of each interstitial site and the strength of the Ni[BOND]H interaction. This indicates the formation of a solid solution.

    9. Microsolvation effects on the stability of polyalanine in extended and polyproline II conformation (pages 3612–3617)

      Joel Ireta

      Version of Record online: 22 JUN 2012 | DOI: 10.1002/qua.24246

      Thumbnail image of graphical abstract

      Microsolvation of a polyalanine chain in fully extended structure and polyproline II conformation is studied using density functional theory. Infinitely long systems are investigated to form infinite networks of hydrogen bonds along the microsolvation shells. It is shown that the interplay between water-water and backbone- water H-bonds clearly stabilizes the polyproline II conformation over the extended on at low microsolvation stages. However, stabilization is abated at large microsolvation stages.

    10. Soft–Soft interactions in the protein–protein recognition process: The K+ channel-charybdotoxin case (pages 3618–3623)

      Felipe Aparicio, Nelly González-Rivas, Joel Ireta, Arturo Rojo, Laura I. Escobar, Andrés Cedillo and Marcelo Galván

      Version of Record online: 16 JUL 2012 | DOI: 10.1002/qua.24278

      Thumbnail image of graphical abstract

      Molecular recognition between peptide blockers and ionic channels is viewed as an interaction in which short-range charge transfer plays a significant role in addition to the most common electrostatic interactions, hydrogen bond formation, and hydrophobicity. Such analysis gives rise to a correlation between global chemicals softness and the dissociation constants for the recognition process. It is worth mentioning that the displayed results establish a link between electronic structure properties and site directed mutagenesis data.

    11. Comparison of molecular graphs of Lin, Nan and Cun (n = 2–5) clusters obtained from the density and the molecular electrostatic potential (pages 3624–3629)

      Patrizia Calaminici, Victor Daniel Domínguez-Soria and Andreas M. Köster

      Version of Record online: 17 JUL 2012 | DOI: 10.1002/qua.24288

      Thumbnail image of graphical abstract

      One of the most challenging tasks in modern chemistry is the description and understanding of the electronic structures of molecules in terms of a bond theory for relevant chemical problems. Molecular graphs of scalar fields such as the electron density result a very powerful tool for this purpose. In this work, the applicability of this feature to alkali metals and transition metal clusters is shown.

    12. Theoretical study of the agostic bond in Me2Al(tBu2pz)2Li(THF) (pages 3630–3636)

      Minhhuy Hô and Ramón Hernández-Lamoneda

      Version of Record online: 30 JUL 2012 | DOI: 10.1002/qua.24294

      Thumbnail image of graphical abstract

      A detailed theoretical study of the agostic bond C—H…Li in Me2Al(tBu2pz)2Li(THF) is performed at the HF and B3LYP levels. The interaction is characterized using structural, energetic, and spectroscopic information which shows an unusually short Li—H distance but a very small barrier for internal rotation of the methyl group indicating the weak nature of this interaction. Topological analysis of the electron density shows a bond path between the Li and the H atoms bent strongly toward the C atom, the first ever reported for agostic interaction involving lithium.

      Corrected by:

      Corrigendum: Corrigendum: Theoretical study of the agostic bond in Me2Al(tBu2pz)2Li(THF)

      Vol. 114, Issue 3, 239, Version of Record online: 30 SEP 2013

    13. UV–Visible properties of oxicams in solution: A TD-DFT and experimental study (pages 3637–3645)

      Marco Franco-Pérez, Luis I. Reyes-García, Rosario Moya-Hernández and Rodolfo Gómez-Balderas

      Version of Record online: 30 JUL 2012 | DOI: 10.1002/qua.24298

      Thumbnail image of graphical abstract

      Microspeciation is of fundamental importance in the study of equilibria in solution. Microspecies involved in prototropic equilibria of isoxicam, piroxicam, meloxicam, tenoxicam, and lornoxicam, five widely used potent anti-inflammatory drugs, are characterized by theoretical and experimental electronic spectrophotometry. Quantum chemistry protocols are able to discern adequately the microspecies in solutions of different polarities and pH.

    14. Density functional theory study of Aun (n = 1–5) clusters supported on montmorillonite (pages 3646–3654)

      Claudia Briones-Jurado, Pablo de la Mora and Esther Agacino-Valdés

      Version of Record online: 3 AUG 2012 | DOI: 10.1002/qua.24308

      Thumbnail image of graphical abstract

      Montmorillonite is a clay mineral with an interlayer space that has been used for anchoring transition-metal catalysts. These systems could be used in pollutant removal. Gold nanoparticles are of special interest because of their unique catalytic properties and delivery applications. The geomerty, stability and electronic properties of gold clusters supported on montmorillonite are studied in this article.

    15. A theoretical study of the confinement of methane in water clusters (pages 3655–3660)

      Graciela Bravo-Pérez and Humberto Saint-Martin

      Version of Record online: 13 AUG 2012 | DOI: 10.1002/qua.24315

      Thumbnail image of graphical abstract

      Understanding the formation of methane hydrates is required to design new and better inhibitors. The study of different clathrates may be helpful to gain insight into the nucleation processes that lead to crystallization. In this work, a comparison is made of the confinement of methane within water clathrates of different sizes, looking into whether a water molecule will engage in an external hydrogen-bond network or in increasing the size of the confining cage.

SEARCH

SEARCH BY CITATION