Cis and trans olefin radicals: equilibrium and photoisomerization

Journal Article · Tue Mar 29 23:00:00 EST 1988 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00215a024· OSTI ID:7076008

Ebbesen, T W; Akaba, R; Tokumaru, K; Washio, M; Tagawa, S; Tabata, Y

Electrochemical reduction of 1,2-bis(1-methyl-4-pyridino)ethylene dication gives the same reduction potentials (-0.53 and -0.72 V vs SCE in CH/sub 3/CN) for both cis and trans isomers. Only the absorbance spectrum of the trans radical (epsilon(max) 57,000 M/sup -1/ cm/sup -1/ at 517 nm) is observed. However, by using pulse radiolysis the radicals of both cis and trans isomers are observed in aqueous solution. Although their absorbance spectra are similar, the extinction coefficients are very different. The cis radical is intrinsically stable but undergoes rapid electron exchange with the trans dication isomer. Cis and trans radicals equilibrate through electron exchange, the limiting rate constants in both directions of the equilibrium being 2 x 10/sup 9/ M/sup -1/ s/sup -1/ (cis to trans) and 3 x 10/sup 8/ M/sup -1/ s/sup -1/ (trans to cis). The photoisomerization of the olefin radicals is essentially one-ray: the quantum yield for the cis radical is 0.2, while that of the trans is less than 0.01.

• Research Organization: Univ. of Notre Dame, IN (USA)
• OSTI ID: 7076008
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:7; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400500* -- Photochemistry
400600 -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
ALKENES
AQUEOUS SOLUTIONS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
DISPERSIONS
EFFICIENCY
EQUILIBRIUM
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOMERIZATION
ISOMERS
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PULSE TECHNIQUES
QUANTUM EFFICIENCY
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
SOLUTIONS
SPECTROSCOPY