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Dimerization Reaction of Regioisomeric Bis(phenylethynyl)benzene Radical Anions during Pulse Radiolysis
Author(s) -
Fujitsuka Mamoru,
Samori Shingo,
Tojo Sachiko,
Haley Michael M.,
Majima Tetsuro
Publication year - 2012
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201200110
Subject(s) - chemistry , phenylacetylene , radiolysis , photochemistry , benzene , dimer , radical ion , electron acceptor , medicinal chemistry , acceptor , reaction rate constant , electron transfer , ultrafast laser spectroscopy , ion , radical , organic chemistry , catalysis , kinetics , spectroscopy , physics , condensed matter physics , quantum mechanics
Abstract Dimerization of a series of regioisomeric 1,4‐, 1,3‐, and 1,2‐bis(phenylethynyl)benzene radical anions (bPEBs .− ) substituted by various electron‐donor and/or electron‐acceptor groups was studied during the pulse radiolysis in N , N ‐dimethylformamide (DMF). The transient absorption of bPEB .− decayed with the formation of new bands attributed to the dimer radical anion of bPEB .− and bPEB (bPEB 2 .− ). From the dependence of decay and formation rates on the concentration of bPEB, the bimolecular rate constants of k b =(1.2±0.1)×10 7 to (3.2±0.2)×10 8 M −1 s −1 were estimated. It is suggested that bPEB .− dimerizes with bPEB through the formation of a CC bond between two sp carbon atoms, to give σ‐type dimer radical anion (σ‐(bPEB) 2 .− ) with a diene‐type structure. The k b values of bPEB .− with bPEB changed with the substitution pattern of the phenylacetylene group on the central benzene ring and the various kinds of donor and/or acceptor group.