Imidazole. pi. cation and barbital. pi. anion trapped in a cocrystalline complex x-irradiated at 12 K: An ESR--ENDOR study

Journal Article · Wed Oct 15 04:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5011554

Kar, L; Bernhard, W A

The predominant free radicals trapped in single crystals of the 1:1 intermolecular complex of imidazole and 5,5-diethylbarbituric acid (barbital) x-irradiated at 12 K have been identified by ESR and ENDOR. The electron abstraction and electron addition products are found to be the imidazole ..pi.. cation and the barbital ..pi.. anion, respectively. The ..pi.. cation provides experimental evidence of evenly distributed unpaired electron density at positions C/sub 2/, C/sub 4/, and C/sub 5/ of the five membered imidazole ring. In the ..pi.. anion the unpaired electron density is localized primarily on C/sub 4/ of barbital. It is suggested that ..pi.. anions are trapped in barbital in preference to imidazole because barbital has a higher cross section for electron capture than imidazole. On the other hand, ..pi.. cations are trapped in imidazole in preference to barbital because the barbital ..pi.. cation has a higher cross section for destruction than the imidazole ..pi.. cation.

• Research Organization: Department of Radiation Biology and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642
• OSTI ID: 5011554
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 73:8; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
AZINES
AZOLES
BARBITURATES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DECOMPOSITION
DRUGS
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
ENDOR
HETEROCYCLIC COMPOUNDS
HYPNOTICS AND SEDATIVES
IMIDAZOLES
IONIZING RADIATIONS
MAGNETIC RESONANCE
MONOCRYSTALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
RESONANCE
TRAPPING
ULTRALOW TEMPERATURE
X RADIATION