Medium effect on the Jahn-Teller distortions of the tetramethylallene radical cation

1991 ◽  
Vol 95 (17) ◽  
pp. 6466-6469 ◽  
Author(s):  
X. Z. Qin ◽  
A. D. Trifunac
Keyword(s):  
Radical Cation ◽  
Medium Effect ◽  
Jahn Teller

scholarly journals Structure and dynamics of the radical cation of ethane arising from the Jahn–Teller and pseudo-Jahn–Teller effects

2018 ◽  
Vol 20 (2) ◽  
pp. 1072-1081 ◽  
Author(s):  
U. Jacovella ◽  
C. J. Stein ◽  
M. Grütter ◽  
L. Freitag ◽  
C. Lauzin ◽  
...  
Keyword(s):  
High Resolution ◽  
Radical Cation ◽  
Photoelectron Spectroscopy ◽  
Structure And Dynamics ◽  
Jahn Teller

High-resolution photoelectron spectroscopy has been used to characterize the structure and dynamics of the ethane radical cation (C2H6+).

Description of Bond Pseudorotation, Bond Pseudolibration, and Ring Pseudoinversion Processes Caused by the Pseudo-Jahn–Teller Effect: Fluoro Derivatives of the Cyclopropane Radical Cation

2014 ◽  
Vol 67 (3) ◽  
pp. 435 ◽  
Author(s):  
Wenli Zou ◽  
Dieter Cremer
Keyword(s):  
Radical Cation ◽  
Positive Charge ◽  
Radical Cations ◽  
Molecular Geometry ◽  
Teller Effect ◽  
Curvilinear Coordinates ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Derivatives Of ◽  
Fluoro Derivatives

Curvilinear coordinates are used to describe the molecular geometry and the pseudo-Jahn–Teller surface of F-substituted cyclopropane radical cations using the equation-of-motion coupled cluster EOMIP-CCSD/cc-pVTZ approach. The monofluoro derivative 2 undergoes bond pseudolibration (incomplete bond pseudorotation) between two symmetry-equivalent biradicaloid forms separated by a barrier of 2.2 kcal mol–1 (1 kcal mol–1 = 4.186 kJ mol–1) at low temperature. Bond pseudorotation and ring pseudoinversion have barriers of 12.1 and 16.5 kcal mol–1 respectively. The relative energies of 2 are affected by the distribution of the positive charge in the C3 ring and the formation of a CF bond with partial π character. There is a change of the CF bond length from 1.285 to 1.338 Å along the bond pseudorotation path. The changes of the CF bond outweigh the deformation effects of the C3 ring; however, both are a result of the pseudo-Jahn–Teller effect according to an (A′ + A′′) ⊗ (a′ + a′′) interaction. For the pentafluoro derivative 3 of the cyclopropane radical cation, bond pseudorotation has a barrier of 16.3 kcal mol–1 whereas ring pseudoinversion is hindered by a barrier of 21.7 kcal mol–1. Radical cation 3 is the first example of a trimethylene radical cation.

An Electron Spin Resonance Investigation of the Radiolysis of Hexamethylbenzene and Hexamethyl(Dewar)Benzene

2003 ◽  
Vol 28 (1) ◽  
pp. 57-74 ◽  
Author(s):  
Christopher J. Rhodes
Keyword(s):  
Radical Cation ◽  
Matrix Material ◽  
Authentic Sample ◽  
Methyl Groups ◽  
Γ Irradiation ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
The Matrix ◽  
Jahn Teller ◽  
Γ Rays

Exposure of hexamethyl(Dewar)benzene (HMD) to γ-rays in a solid CFC13 matrix at 77K generated the corresponding radical cation (HMD+•) as shown by the observation of hyperfine coupling (A = 9·5 G) to the protons of four equivalent methyl groups: thus the 2B2 state (I) of the ion is established. On annealing to 140 K, ring-opening occurred to give the hexamethylbenzene cation (HMB+•). When CF2ClCFCl2 was used as the matrix material, a completely different spectrum was produced, consisting of seven lines with a common spacing of 14 G. Results obtained using different batches of the freon, and from careful annealing and concentration studies, establish that the low-field line is not part of the remaining six-line spectrum which can be assigned to the allylic radical (III), formed by deprotonation of the parent cation. γ-Irradiation of HMD in 2- methyltetrahydro-furan (MeTHF) followed by annealing gave the ψs* Jahn-Teller distorted form of the (ring-opened) HMB-• radical anion [A(6H) = 9 G] and so the parent anion is unstable, as is the cation. This was confirmed by an identical spectrum being obtained after the irradiation of an authentic sample of HMB in MeTHF. γ-Irradiation of pure HMD gave rise to a spectrum that can be analysed in terms of (III) and the endo H-atom adduct of HMD (IV). Hexamethylbenzene (HMB) on γ-irradiation in solid CFC13 gave the parent radical cation (HMB+•) At 130 K, this has a 6·7 G splitting and correct binomial intensities for 18 equivalent protons; on cooling to 77 K, the cation distorts so that a ψA type SOMO is adopted with four strongly coupled (A = 11·5G) and two weakly coupled (A = −2·8G) methyl groups. γ-Irradiation of pure HMB gave only broad features which we ascribe to a mixture of pentamethylbenzyl (VIII) and hexamethylcyclohexadienyl (IX) radicals, in which proton hyperfine structure is unresolved due to a range of restricted conformations being adopted by various methyl groups because of steric hindrance between them.

Energy component analysis of the Jahn–Teller effect in the methane radical cation

1991 ◽  
Vol 94 (12) ◽  
pp. 8083-8088 ◽  
Author(s):  
Russell J. Boyd ◽  
Katherine Valenta Darvesh ◽  
Paul D. Fricker
Keyword(s):  
Radical Cation ◽  
Component Analysis ◽  
Teller Effect ◽  
Energy Component ◽  
Jahn Teller ◽  
Jahn Teller Effect
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