Isotope effects in the electron spin resonance spectra of deuterated triphenylmethyl radicals

Journal Article · Thu Jun 21 04:00:00 EDT 1984 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150657a007· OSTI ID:6765532

Trapp, C; Kulkarni, S V

The EPR spectra of a series of five symmetrically deuterated triphenylmethyl radicals were investigated in order to provide a critical test of the vibrational model of the deuterium isotope effect in an odd-alternant aromatic system. The experimentally determined values of k (eq 2) are k > 1 at para and ortho positions and k < 1 at meta positions, whereas the vibrational model predicts the reverse. Spin density calculations using Coulomb and resonance integral perturbations at deuterium-substituted positions indicate that the effect cannot be explained as a result of spin density changes upon deuteration. The observed changes in hydrogen hyperfine splitting constants (a/sup H/) at undeuterated positions, however, do qualitatively agree with the calculated spin density changes. The results indicate that the deuterium isotope effect in complex radicals agree with the calculated spin density changes. The results indicate that the deuterium isotope effect in complex radicals such as triphenylmethyl cannot be interpreted simply as a result of out of plane vibrations of a -(CH)/sub 2/C-H fragment. 27 references, 5 figures, 5 tables.

• Research Organization: Univ. of Louisville, KY
• OSTI ID: 6765532
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 88:13; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
DATA
DEUTERIUM
EXPERIMENTAL DATA
HYDROGEN ISOTOPES
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
STABLE ISOTOPES