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Spin‐coupled study of addition reactions of singlet dihalocarbenes with ethene
Author(s) -
Blavins Joshua J.,
Cooper David L.,
Karadakov Peter B.
Publication year - 2004
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.20081
Subject(s) - diradical , chemistry , cyclopropane , carbene , singlet state , valence bond theory , generalized valence bond , spins , computational chemistry , single bond , photochemistry , ring (chemistry) , molecular orbital , molecule , atomic physics , physics , excited state , alkyl , organic chemistry , condensed matter physics , catalysis
Modern valence bond theory, in its spin‐coupled form, is used to examine the electronic rearrangements that take place during the gas‐phase additions of singlet CF 2 and of singlet CCl 2 to ethene. Both reactions are found to follow homolytic pathways, during which the ethene π‐bond breaks and the orbitals that were originally involved in this bond interact with the singlet orbital pair on the carbene. The formation of the two new σ bonds that close the cyclopropane ring proceeds in a markedly asynchronous manner, so that the systems attain considerable diradical character, as quantified by the composition of the active‐space spin‐coupling pattern. The rearrangement of the electron spins from a reactant‐like form to one better suited to the product takes place much later in the case of the reaction between CCl 2 and ethene than in the corresponding reaction of CF 2 . © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004