Jenny Zevallos | Universidad Tecnologica del Peru UTP (original) (raw)

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Guilherme Moerbeck

UERJ - Universidade do Estado do Rio de Janeiro / Rio de Janeiro State University

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Papers by Jenny Zevallos

Journal of Physical Chemistry A, 2004

ABSTRACT

Journal of The Chilean Chemical Society, 2003

... 9. PMW Gill "Encyclopedia of Computational Chemistry" John Wiley & Song: New Yo... more ... 9. PMW Gill "Encyclopedia of Computational Chemistry" John Wiley & Song: New York 1998. [ Links ]. 10. P. Hohenberg and W. Kohn Phys. Rev. B. 1964, 136, 864. [ Links ]. 11. ... 1990, 11, 1206. [ Links ]. 37. AD McLean and GS Chandler J. Chem. Phys. 1980, 72, 5639. [ Links ]. 38 ...

Journal of Physical Chemistry A, 2001

Two intramolecular rearrangement reactions trans-N 2 H 2 → cis-N 2 H 2 and F 2 S 2 → FSSF have be... more Two intramolecular rearrangement reactions trans-N 2 H 2 → cis-N 2 H 2 and F 2 S 2 → FSSF have been studied in both gas and solution phases using the ab initio SCF method at the Hartree−Fock level as well as using density functional theory with B3LYP exchange-...

Journal of Molecular Structure-theochem, 2002

We present a density functional theory (DFT) study of the solvent effects on two intramolecular r... more We present a density functional theory (DFT) study of the solvent effects on two intramolecular rearrangements. We have used relative values of energy, electronic chemical potential, chemical hardness and dipole polarizability as global descriptors to analyze the trans-N 2 H 2 ! cis-N 2 H 2 and F 2 S 2 ! FSSF rearrangements in gas and solution phases. Our results agree well with the maximum hardness principle and the minimum polarizability principle. Both reactions become thermodynamically and kinetically more favorable, in the condensed phase. All the species associated with these reactions become less electrophilic in the presence of a polarizable environment. The lowering in the electrophilicity of the species upon solvation may be partitioned into two contributions. The ®rst one contains the variations in electronic chemical potential for the change of phase; whereas the second one indirectly encompasses the variations in chemical hardness through the changes in the maximum charge transfer to the environment. For both reactions, the electronic chemical potential and chemical hardness variations cooperatively contribute to the loss in the electrophilicity power from the gas to solution phase. q

Structural Chemistry, 2005

High level ab initio and density functional theory calculations have been carried out to investig... more High level ab initio and density functional theory calculations have been carried out to investigate the relative stability of the different conformers of hyponitrous acid and its mono- and dithio-derivatives. Geometries and vibrational frequencies were obtained at the B3LYP/6-311+G(d,p) level and final energies through B3LYP/6-311++G(3df,2pd) single point calculations. The reliability of this theoretical scheme has been assessed by comparing these DFT results with those obtained at the G3 level of theory, for some suitable cases. The cis conformers of hyponitrous acid and its mono- and dithio-derivatives are systematically more stable than the trans ones because in the cis conformation a dative interaction between the nitrogen-lone pairs and the σNX^* antibonding orbital is significantly favored. Quite interestingly, in general, the conformers presenting an intramolecular hydrogen bond (IHB) are not the global minima of the corresponding potential energy surfaces and only for hyponitrous acid the conformer with a OH ⋅s O IHB is slightly more stable than the cis conformer without IHB. The low stability of the tautomers with IHB is closely related with another weak intramolecular interaction which involves the lone-pairs of the chalcogen atoms and the πNN* antibondig orbital, and which is significantly perturbed when the IHB is formed.

Journal of Physical Chemistry A, 2004

ABSTRACT

Journal of The Chilean Chemical Society, 2003

... 9. PMW Gill "Encyclopedia of Computational Chemistry" John Wiley & Song: New Yo... more ... 9. PMW Gill "Encyclopedia of Computational Chemistry" John Wiley & Song: New York 1998. [ Links ]. 10. P. Hohenberg and W. Kohn Phys. Rev. B. 1964, 136, 864. [ Links ]. 11. ... 1990, 11, 1206. [ Links ]. 37. AD McLean and GS Chandler J. Chem. Phys. 1980, 72, 5639. [ Links ]. 38 ...

Journal of Physical Chemistry A, 2001

Two intramolecular rearrangement reactions trans-N 2 H 2 → cis-N 2 H 2 and F 2 S 2 → FSSF have be... more Two intramolecular rearrangement reactions trans-N 2 H 2 → cis-N 2 H 2 and F 2 S 2 → FSSF have been studied in both gas and solution phases using the ab initio SCF method at the Hartree−Fock level as well as using density functional theory with B3LYP exchange-...

Journal of Molecular Structure-theochem, 2002

We present a density functional theory (DFT) study of the solvent effects on two intramolecular r... more We present a density functional theory (DFT) study of the solvent effects on two intramolecular rearrangements. We have used relative values of energy, electronic chemical potential, chemical hardness and dipole polarizability as global descriptors to analyze the trans-N 2 H 2 ! cis-N 2 H 2 and F 2 S 2 ! FSSF rearrangements in gas and solution phases. Our results agree well with the maximum hardness principle and the minimum polarizability principle. Both reactions become thermodynamically and kinetically more favorable, in the condensed phase. All the species associated with these reactions become less electrophilic in the presence of a polarizable environment. The lowering in the electrophilicity of the species upon solvation may be partitioned into two contributions. The ®rst one contains the variations in electronic chemical potential for the change of phase; whereas the second one indirectly encompasses the variations in chemical hardness through the changes in the maximum charge transfer to the environment. For both reactions, the electronic chemical potential and chemical hardness variations cooperatively contribute to the loss in the electrophilicity power from the gas to solution phase. q

Structural Chemistry, 2005

High level ab initio and density functional theory calculations have been carried out to investig... more High level ab initio and density functional theory calculations have been carried out to investigate the relative stability of the different conformers of hyponitrous acid and its mono- and dithio-derivatives. Geometries and vibrational frequencies were obtained at the B3LYP/6-311+G(d,p) level and final energies through B3LYP/6-311++G(3df,2pd) single point calculations. The reliability of this theoretical scheme has been assessed by comparing these DFT results with those obtained at the G3 level of theory, for some suitable cases. The cis conformers of hyponitrous acid and its mono- and dithio-derivatives are systematically more stable than the trans ones because in the cis conformation a dative interaction between the nitrogen-lone pairs and the σNX^* antibonding orbital is significantly favored. Quite interestingly, in general, the conformers presenting an intramolecular hydrogen bond (IHB) are not the global minima of the corresponding potential energy surfaces and only for hyponitrous acid the conformer with a OH ⋅s O IHB is slightly more stable than the cis conformer without IHB. The low stability of the tautomers with IHB is closely related with another weak intramolecular interaction which involves the lone-pairs of the chalcogen atoms and the πNN* antibondig orbital, and which is significantly perturbed when the IHB is formed.

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