Hardness Profile and Activation Hardness for Rotational Isomerization Processes. 1. Application to Nitrous Acid and Hydrogen Persulfide

Cárdenas-Jirón, Gloria I.; Lahsen, Joaquín; Toro–Labbé, Alejandro

doi:10.1021/j100015a014

Cited by 52 publications

(77 citation statements)

References 14 publications

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“…The two-center coulomb repulsion term, E J AB is E J AB = P A P B γ AB (10) γ AB is the electronic repulsion between an electron on atom A and an electron on atom B;…”

Section: Necessary Algorithmmentioning

confidence: 99%

“…It appears from the survey of literature on the origin of barrier to internal rotation of molecules that majority of workers believe that it is a regional effect and barrier originates from some mystic reason. The physical process of generation of Cis Trans and Staggered Eclipsed conformers is in fact a rotational isomerization process and can be viewed as resulting from reorganization and redistribution of electron density among the atoms in a molecule, so that the total number of electrons is conserved even though there may be an intramolecular charge transfer process [9,10]. Thus the physical process of the dynamics of internal rotation initiates the isomerization reaction, which generates infinite number of conformations between the extreme conformations stated above.…”

Section: Introductionmentioning

confidence: 99%

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A Quest for the Origin of Barrier to the Internal Rotation ofHydrogen Peroxide (H2O2) and Fluorine Peroxide (F2O2)

Ghosh

2006

IJMS

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Abstract:In order to understand the structure-property relationship, SPR, an energypartitioning quest for the origin of the barrier to the internal rotation of two iso-structural molecules, hydrogen peroxide, H 2 O 2 , and fluorine peroxide, F 2 O 2 is performed. The hydrogen peroxide is an important bio-oxidative compound generated in the body cells to fight infections and is an essential ingredient of our immune system. The fluorine peroxide is its analogue. We have tried to discern the interactions and energetic effects that entail the nonplanar skew conformation as the equilibrium shape of the molecules. The physical process of the dynamics of internal rotation initiates the isomerization reaction and generates infinite number of conformations. The decomposed energy components faithfully display the physical process of skewing and eclipsing as a function of torsional angles and hence are good descriptors of the process of isomerization reaction of hydrogen peroxide (H 2 O 2 ) and dioxygen difluoride (F 2 O 2 ) associated with the dynamics of internal rotation. It is observed that the one-center, two-center bonded and nonbonded interaction terms are sharply divided in two groups. One group of interactions hinders the skewing and favours planar cis/trans forms while the other group favours skewing and prefers the gauche conformation of the molecule. The principal energetic effect forcing the molecules into the nonplanar gauche form is the variation "O-O' bond energy with torsion in both the molecules. It is demonstrated that the barrier is not a regional effect rather it is made by the conjoint action of all one-and two-center bonding and nonbonding interactions comprising the entire framework of the molecule. The present study claims to reveal one amazing feature of nonbonded interactions. Computed results of nonbonding interactions demonstrate that the nature of interaction between two formally positively charged non-bonding H atoms (H δ+ ----

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“…The two-center coulomb repulsion term, E J AB is E J AB = P A P B γ AB (10) γ AB is the electronic repulsion between an electron on atom A and an electron on atom B;…”

Section: Necessary Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Quest for the Origin of Barrier to the Internal Rotation ofHydrogen Peroxide (H2O2) and Fluorine Peroxide (F2O2)

Ghosh

2006

IJMS

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“…͑5͒ or ͑7͒. 19,29 For a given nontotally symmetric nuclear distortion, hardnesses obtained from Eq. ͑7͒ tend to disobey more often the GMHP than those calculated from Eq.…”

Section: A the Benzene Molecule As A Test Examplementioning

confidence: 99%

“…However, relaxation of these constraints seems to be permissible, and in particular, it has been found that in most cases the MHP still holds even though the chemical and external potentials vary during the molecular vibration, internal rotation or along the reaction coordinate. 12,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Hereafter, we will refer to the generalized MHP ͑GMHP͒ or MPP ͑GMPP͒ as the maximum hardness or minimum polarizability principles that do not require the constancy of chemical and external potentials during molecular change. It is worth emphasizing that the generalized versions of these principles have not been proven.…”

Section: Introductionmentioning

confidence: 99%

Are the maximum hardness and minimum polarizability principles always obeyed in nontotally symmetric vibrations?

Torrent‐Sucarrat

Luis

Duran

et al. 2002

The Journal of Chemical Physics

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In a recent paper ͓J. Am. Chem. Soc. 123, 7951 ͑2001͔͒ we have shown for the first time the existence of molecules with nontotally symmetric vibrational modes that break the maximum hardness ͑MHP͒ and minimum polarizability ͑MPP͒ principles. We present here an extension of this previous work by devising a mathematical procedure that helps to determine the nontotally symmetric molecular distortions of a given molecule that do not follow the MPP or the MHP. This methodology is based on the diagonalization of the Hessian matrix of the polarizability or the hardness with respect to the vibrational normal coordinates. For a relatively large series of molecules, we have carried out diagonalizations of the Hessian matrix of the polarizability to determine the molecular distortions with a more marked MPP or anti-MPP character. From the results obtained, we have derived a set of simple rules that allow to predict a priori without calculations the existence of vibrational modes that break the MPP. With respect to the MHP, the results strongly depend on the method of calculation, but the same rules are useful to predict the existence of vibrational modes that disobey the MHP when the Koopmans' approximation is used to calculate the hardness.

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“…The formal proof of the MHP was given by Parr and Chattaraj [5]. Although this proof has been criticized [6], the relevance of the MHP in molecular internal rotation processes has been pointed out in several publications [7,8]. However, various exceptions to this principle have been found.…”

Section: Introductionmentioning

confidence: 99%

Internal rotation of fluorinated butane compounds

Lahsen

Ramos‐Grez

2006

Journal of Fluorine Chemistry

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Hardness Profile and Activation Hardness for Rotational Isomerization Processes. 1. Application to Nitrous Acid and Hydrogen Persulfide

Cited by 52 publications

References 14 publications

A Quest for the Origin of Barrier to the Internal Rotation ofHydrogen Peroxide (H2O2) and Fluorine Peroxide (F2O2)

A Quest for the Origin of Barrier to the Internal Rotation ofHydrogen Peroxide (H2O2) and Fluorine Peroxide (F2O2)

Are the maximum hardness and minimum polarizability principles always obeyed in nontotally symmetric vibrations?

Internal rotation of fluorinated butane compounds

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