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Gas‐Phase Synthesis of the Benzyl Radical (C 6 H 5 CH 2 )
Author(s) -
Dangi Beni B.,
Parker Dorian S. N.,
Yang Tao,
Kaiser Ralf I.,
Mebel Alexander M.
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201310612
Subject(s) - crossed molecular beam , chemistry , isomerization , singlet state , isoprene , methyl radical , radical , photochemistry , potential energy surface , molecule , ab initio , computational chemistry , atomic physics , excited state , organic chemistry , catalysis , physics , polymer , copolymer
Dicarbon (C 2 ), the simplest bare carbon molecule, is ubiquitous in the interstellar medium and in combustion flames. A gas‐phase synthesis is presented of the benzyl radical (C 6 H 5 CH 2 ) by the crossed molecular beam reaction of dicarbon, C 2 (X 1 Σ g + , a 3 Π u ), with 2‐methyl‐1,3‐butadiene (isoprene; C 5 H 8 ; X 1 A′) accessing the triplet and singlet C 7 H 8 potential energy surfaces (PESs) under single collision conditions. The experimental data combined with ab initio and statistical calculations reveal the underlying reaction mechanism and chemical dynamics. On the singlet and triplet surfaces, the reactions involve indirect scattering dynamics and are initiated by the barrierless addition of dicarbon to the carbon–carbon double bond of the 2‐methyl‐1,3‐butadiene molecule. These initial addition complexes rearrange via multiple isomerization steps, leading eventually to the formation of C 7 H 7 radical species through atomic hydrogen elimination. The benzyl radical (C 6 H 5 CH 2 ), the thermodynamically most stable C 7 H 7 isomer, is determined as the major product.