Browsing by Author "Gutierrez Oliva, S"

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    Towards understanding the molecular internal rotations and vibrations and chemical reactions through the profiles of reactivity and selectivity indices: an ab initio SCF and DFT study
    (TAYLOR & FRANCIS LTD, 2003) Chattaraj, PK; Gutierrez Oliva, S; Jaque, P; Toro Labbe, A
    Ab initio SCF and DFT(B3LYP) calculations are performed with 6-311G** basis sets for obtaining insights into molecular internal rotations in HXNX (X=O,S), different vibrational modes in water and double proton transfer reaction in (HONO)(2). While chemical reactivity is analyzed in terms of the pro. le of the global reactivity parameters, such as energy, chemical potential, hardness, polarizability, molecular valency and electrophilicity indices, the site selectivity is understood through the variations in local descriptors, such as the Fukui function and atomic valency. Principles of maximum hardness and molecular valency and the minimum polarizability principle are found to be valid in almost all cases. Rotational isomerization reactions can be better characterized by making use of the maximum hardness principle along with Hammond's postulate. Extremum points in electrophilicity during internal rotations, vibrations and chemical reaction can be located from those of chemical potential and hardness. The Fukui function and atomic valency show inverse behaviour in most cases.
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    Using Sanderson's principle to estimate global electronic properties and bond energies of hydrogen-bonded complexes
    (AMER CHEMICAL SOC, 2000) Gutierrez Oliva, S; Jaque, P; Toro Labbe, A
    In this paper, we use Sanderson's geometric mean equalization principle for electronegativity (chi) to derive expressions for molecular hardness (eta) and its derivative (gamma) that are used to estimate the electronic properties of 14 molecules and bimolecular hydrogen-bonded complexes. Beyond the determination of electronic properties, it is shown that Sanderson's scheme can be very useful as a method for rationalizing chemical reactions when both N and upsilon change. We have found that the conditions of maximum hardness and minimum polarizability complement the minimum energy criterion for stability of molecular aggregates. Finally, we propose a new scheme for obtaining molecular properties from the isolated fragments that produces results that are in excellent agreement with those determined through Sanderson's scheme.