Bonding in singlet and triplet butalene: insights from spin-coupled theory

David L Cooper, Peter B Karadakov, Brian J Duke

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3 Citations (Scopus)


Spin-coupled (SC, equivalent to full generalized valence bond) calculations for the 1Ag ground state of butalene at its optimal D2h planar geometry show that cross-ring Dewar-like modes of spin coupling are of comparable importance to the more usually considered Kekulé-like modes. There are marked similarities to the SC description of one of the isomers of benzo[1,2:4,5]dicyclobutadiene. A complication for both of these systems is the existence of SC solutions in which some of the orbitals resemble in- and out-of-phase combinations of semilocalized atom-centered orbitals. The lowest triplet state, for which a nonplanar C2v geometry is preferred, is somewhat more straightforward to analyze: the SC description of the 3B2 state is dominated by a very simple pattern of two π bonds and two well-localized triplet-coupled orbitals.
Original languageEnglish
Pages (from-to)2169-2175
Number of pages7
JournalThe Journal of Physical Chemistry A
Issue number10
Publication statusPublished - 2015

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