scholarly journals Stabilization Energy and Spin Distribution in Pyrenophane Cation Radicals

1982 ◽  
Vol 55 (12) ◽  
pp. 3896-3898 ◽  
Author(s):  
Atsushi Terahara ◽  
Hiroaki Ohya-Nishiguchi ◽  
Noboru Hirota ◽  
Yoshiteru Sakata ◽  
Soichi Misumi ◽  
...  
Keyword(s):  
Stabilization Energy ◽  
Spin Distribution ◽  
Cation Radicals

Transannular interactions in dimer cation radicals of naphthalene derivatives. Conformation anomaly and stabilization energy

1986 ◽  
Vol 90 (8) ◽  
pp. 1564-1571 ◽  
Author(s):  
Atsushi Terahara ◽  
Hiroaki Ohya-Nishiguchi ◽  
Noboru Hirota ◽  
Akira Oku
Keyword(s):  
Stabilization Energy ◽  
Naphthalene Derivatives ◽  
Cation Radicals

1H, 13C, 14N, 19F Nuclear Magnetic Resonance Contact Shifts and Electron Spin Distribution in Aniline and Fluoroanilines – Ni(II) Acetylacetonate Complexes

1975 ◽  
Vol 53 (5) ◽  
pp. 648-660 ◽  
Author(s):  
C. Chachaty ◽  
A. Forchioni ◽  
J. Virlet
Keyword(s):  
Electron Spin ◽  
Hyperfine Coupling ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Spin Distribution ◽  
Spin Lattice ◽  
Cation Radicals ◽  
Text Fragment

The contact shifts of 1H, 13C, 14N, and 19F in chloroform solutions of Ni(II) acetylacetonate -aniline and fluoraniline complexes have been studied by high resolution n.m.r. The unpaired electron spin distribution in these ligands is compared to that calculated by the INDO method for the corresponding aniline cation radicals. The ratio of the hyperfine coupling constants aNHH/aN suggests that in these aniline complexes the [Formula: see text] fragment is pyramidal with an angle of 13–15° between the perpendicular of the C—N bond and the axis of the p like orbital centered on nitrogen. The electron spin distribution between the NH2 group and the phenyl ring may be partially accounted for by assuming an internal rotation about the C—N bond. The 13C relaxation indicates a N—Ni distance of the order of 2 Å for aniline and 2 fluoraniline complexes and an electron spin-lattice relaxation time of ∼5 × 10−10 s at 300 °K.

ESR-und ENDOR-Untersuchungen der Autoxidationsprodukte des Adrenalons und analoger Verbindungen / ESR and ENDOR Investigations of the Autoxidation Products of Adrenalone and Related Compounds

1986 ◽  
Vol 41 (6) ◽  
pp. 776-780 ◽  
Author(s):  
Hartmut B. Stegmann ◽  
Klaus Stolze ◽  
Klaus Scheffler
Keyword(s):  
Carbonyl Group ◽  
Coupling Constants ◽  
Triple Resonance ◽  
Semiquinone Radical ◽  
Spin Distribution ◽  
Subsequent Oxidation ◽  
Cation Radicals ◽  
Proton Coupling ◽  
Selective Deuteration ◽  
Related Compounds

Abstract The signs of the proton coupling constants of adrenalone semiquinone and related compounds were determined by ENDOR and TRIPLE resonance studies, thereby verifying the increment system described in our previous paper [2], Comparison of the spin-distribution of several substituted acylcatechols showed the conformational influence on the coupling constants due to mesomeric interaction of the carbonyl group with the aromatic π-system. Adrenalone and other N -monosubstituted catecholamines showed rather stable secondary radi­cals after the decay of the primary semiquinone radical. They were identified as substituted dihydropyrazinium cation radicals after selective deuteration and comparison of their ESR-, ENDOR- and TRIPLE-resonance spectra with those of the non-deuterated species. They are formed by cyclic condensation of two molecules with subsequent oxidation.

Quantum-chemical analysis of small silver clusters

1987 ◽  
Vol 52 (7) ◽  
pp. 1652-1657 ◽  
Author(s):  
Grigorii V. Gadiyak ◽  
Yurii N. Morokov ◽  
Mojmír Tomášek
Keyword(s):  
Hard Spheres ◽  
Electronic Configuration ◽  
Close Packing ◽  
Basis Sets ◽  
Silver Clusters ◽  
Quantum Chemical Analysis ◽  
Spin Distribution ◽  
Spin Polarized ◽  
Atomic Silver ◽  
Equilibrium Geometries

Total energy calculations of three- and four-atomic silver clusters have been performed by the spin-polarized version of the CNDO/2 method to get the most stable equilibrium geometries, atomization energies, and charge and spin distribution on the atoms for three different basis sets: {s}, {sp}, and {spd}. When viewed from the equilateral triangle and square geometries, the last electronic configuration, i.e. the {spd} one, appears to be most stable with respect to the geometrical deformations considered. In this case, the behaviour of the atoms of both clusters resembles that of hard spheres (i.e. close-packing).

Properties and Reactivity of First and Second Row Hydrides. IV. Interactions Between Hydrides and Their Radical Ions

1993 ◽  
Vol 58 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Rudolf Zahradník
Keyword(s):  
Radical Cations ◽  
Stabilization Energy ◽  
Hydrogen Atom Abstraction ◽  
Type Ii ◽  
Radical Ions ◽  
Reaction Products ◽  
Ion Molecule Reactions ◽  
Heats Of Reaction ◽  
Experimental Values ◽  
Easy Differentiation

The energies and heats of ion-molecule reactions have been calculated (MP4/6-31G**//6-31G** or better level) and compared with the experimental values obtained from the heats of formation. Two main types of reactions have been studied: (i) AHn + AHn+• ↔ AHn+1+ + AHn-1• (A = C to F and Si to Cl), (ii) AHn + BHm+• ↔ AHn+1+ + BHm-1• or AHn-1+• + BHm+1+ (A and B = C to F). In contrast to (i), processes of type (ii) permit easy differentiation between the proton transfer and hydrogen atom abstraction mechanisms. A third type of interaction involves reactions with radical anions (A = Li to F); comparison was made with analogous processes with radical cations. A brief comment is made about the influence of the level of computational sophistication on the energies and heats of reaction, as well as on the stabilization energy of a hydrogen bonded intermediate, a structure which is similar to that of the reaction products.

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