Molecular‐Orbital Theory of Geometry and Hyperfine Coupling Constants of Fluorinated Methyl Radicals

1968 ◽  
Vol 48 (10) ◽  
pp. 4802-4803 ◽  
Author(s):  
David L. Beveridge ◽  
Paul A. Dobosh ◽  
J. A. Pople
Keyword(s):  
Molecular Orbital ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Molecular Orbital Theory ◽  
Methyl Radicals ◽  
Orbital Theory ◽  
Hyperfine Coupling Constants

E.P.R. studies of the anions of some peri-alkylnaphthalenes

1972 ◽  
Vol 25 (11) ◽  
pp. 2353 ◽  
Author(s):  
RFC Claridge ◽  
BM Peake
Keyword(s):  
Electron Spin Resonance ◽  
Molecular Orbital ◽  
Electron Spin ◽  
Hyperfine Coupling ◽  
Inductive Effect ◽  
Coupling Constants ◽  
Radical Anions ◽  
Hyperfine Coupling Constants ◽  
Spin Resonance ◽  
Aliphatic Substituent

The hyperfine coupling constants for the radical anions of 2,3-dihydro- phenalene (perinaphthane) and 7,8,9,l0-tetrahydrocyclohepta[de]naphthalene have been determined from analysis of the electron spin resonance spectra in solution. The results are compared with data from other mono- and di-peri- substituted naphthalenes. A simple H�ckel molecular orbital treatment is used to describe the inductive effect of the aliphatic substituent.

Activation Parameters for Ring Opening of (Bicyclo[n.1.1]alk-1-yl)methyl Radicals

1991 ◽  
Vol 44 (10) ◽  
pp. 1417 ◽  
Author(s):  
PE Pigou ◽  
DK Taylor
Keyword(s):  
Molecular Orbital ◽  
Energy Barrier ◽  
Ring Opening ◽  
Activation Parameters ◽  
Molecular Orbital Theory ◽  
Methyl Radicals ◽  
Orbital Theory ◽  
Semiempirical Molecular Orbital

Ring opening of the (bicyclo[1.1.1]pent-1-yl)methyl (4), (bicyclo[2.1.1]hex-1-yl)methyl (5) and (bicyclo[3.1.1]hept-1-yl)methyl (6) radicals has been investigated by semiempirical molecular orbital theory MINDO/3 and AM1) and by experiment. Our results indicate that (4) ring-opens extremely rapidly, with an estimated energy barrier of less than 22 kJ mol-1. The higher homologues (5) and (6) rearrange more slowly with barriers of about 42.2 and 46.0 kJ mol-1 respectively. This trend is also observed in the MINDO/3 and AM1 results, with the latter giving the better agreement with experiment.

Long-range 1H,19F and 13C,19F coupling constants and molecular orbital computations as indicators of internal motion in C6H5OCF3 and its 4-fluoro derivative

1991 ◽  
Vol 69 (7) ◽  
pp. 1047-1053 ◽  
Author(s):  
Ted Schaefer ◽  
Glenn H. Penner ◽  
Rudy Sebastian ◽  
James Peeling ◽  
Christian Beaulieu
Keyword(s):  
Molecular Orbital ◽  
Long Range ◽  
Solvent Polarity ◽  
Coupling Constants ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
H Nmr ◽  
Fluoro Derivative ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nonpolar Solution

Internal rotational potentials for rotation about the Csp2—O bond in C6H5OCF3 and its 4-fluoro derivative are computed at the STO-3G and 3-12G levels of molecular orbital theory. As for anisole, the perpendicular conformer is calculated as least stable for C6H5OCF3 but the height of the internal barrier is considerably lower than in anisole. The 4-fluoro substituent reduces the twofold component significantly, indicating reduced p …π conjugation, but does not much change the values of the higher terms in the theoretical potentials. The internal potentials are rather flat with minima between about 30° and 45°, these angles measuring the twist away from planarity. The 1H, 13C, and 19F nuclear magnetic resonance spectra in polar and nonpolar solution yield long-range coupling constants, nJ(1H,19F) and nJ(13C,19F). These parameters are qualitatively consistent with relatively low barriers to rotation about the Csp2—O bonds in these molecules and with only a small dependence on solvent polarity. Key words: C6H5OCF3 and 4-F-C6H4OCF3: 1H NMR, 19F NMR, conformations, MO computations.

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