Electron-transfer-sensitized C-C bond cleavage. Facile homolytic fission via geminate back electron transfer in photogenerated ion pairs

Journal Article · Sun Jan 01 04:00:00 EST 1984 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00335a017· OSTI ID:5973450

Davis, H F; Das, P K; Reichel, L W; Griffin, G W

Several organic substrates (donors) known to undergo oxidative C-C bond cleavage upon steady-state irradiation under electron-transfer photosensitization have been examined by 337.1 nm laser flash photolysis for photoproduction of substrate radicals/radical cations and sensitizer triplet as a result of charger-transfer interaction with 1,4-dicyanonaphthalene (DCN) single (acceptor). The transient-absorption phenomena and quantitative estimates of electron-transfer-mediated yields show that for substrates such as 1-(diphenylmethyl)cyclohepta-2,4,6-triene and aryl-substituted pinacols and pinacol-ethers characterized by relatively unstable, short-lived, radical cations, a substantial fraction of arylmethyl radicals are generated fast via back electron transfer in the photogenerated ion pair. In other cases, longer lived radical cations (solvated) that either undergo intramolecular electron transfer leading to C-C bond fragmentation (e.g., with 1,1,2,2-tetraphenylethane) or diffusional back donation of electron from the DCN radical anion (e.g., with p-methoxy- and p-methyl-substituted bibenzyls). Within small groups of closely related quenchers, radical and radical ion yields are found to depend systematically on the structures, chemical nature, and oxidation potentials of the substrates. 18 references, 5 figures, 1 table.

• Research Organization: Univ. of Notre Dame, IN
• OSTI ID: 5973450
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 106:23; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500* -- Photochemistry
ALCOHOLS
AROMATICS
CHEMISTRY
CONDENSED AROMATICS
DATA
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
ETHERS
EXPERIMENTAL DATA
GLYCOLS
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
LASER RADIATION
NAPHTHALENE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMISTRY
PINACOL
RADIATIONS
RADICALS