Semiempirical investigation of stilbene-linked diradicals and magnetic study of their bis(N-tert-butylnitroxide) variants

Naoki Yoshioka, Paul M. Lahti, Takashi Kaneko, Yoshihiro Kuzumaki, Eishun Tsuchida, Hiroyuki Nishide

Research output: Contribution to journalArticle

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Abstract

The electronic states of open-shell stilbene diradicals were studied. Previously used semiempirical MO-CI methods were applied to stilbenes having dimethylene, dioxyl, and dinitroxide centers in o,o′-, o,m′-, o,p′-, m,m′-, m,p′-, and p,p′-substitution patterns, and the various singlet-triplet energy gaps were computed to predict qualitative ground state spin multiplicities. Singlet and triplet spin states were essentially degenerate in the m,m′-isomers of disjoint connectivity, while nondisjoint o,m′- and m,p′-isomers had triplet computed ground states. Nitroxide-based diradicals showed considerably smaller computational exchange coupling energies than did other diradical models studied. As a tests of these computations, stilbenes with two N-tert-butyl nitroxide groups at the o,m′-, m,m′-, and m,p′-positions were prepared, and their magnetic properties were studied by ESR and magnetic susceptibility measurements. The m,m′- and m,p′-isomers were found experimentally to have singlet and triplet ground states, respectively, in accord with the qualitative computed predictions.

Original languageEnglish
Pages (from-to)4272-4280
Number of pages9
JournalJournal of Organic Chemistry
Volume59
Issue number15
Publication statusPublished - 1994

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Stilbenes
Isomers
Ground state
Exchange coupling
Electronic states
Magnetic susceptibility
Paramagnetic resonance
Magnetic properties
Energy gap
Substitution reactions
tert-butylnitroxide

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Semiempirical investigation of stilbene-linked diradicals and magnetic study of their bis(N-tert-butylnitroxide) variants. / Yoshioka, Naoki; Lahti, Paul M.; Kaneko, Takashi; Kuzumaki, Yoshihiro; Tsuchida, Eishun; Nishide, Hiroyuki.

In: Journal of Organic Chemistry, Vol. 59, No. 15, 1994, p. 4272-4280.

Research output: Contribution to journalArticle

Yoshioka, Naoki ; Lahti, Paul M. ; Kaneko, Takashi ; Kuzumaki, Yoshihiro ; Tsuchida, Eishun ; Nishide, Hiroyuki. / Semiempirical investigation of stilbene-linked diradicals and magnetic study of their bis(N-tert-butylnitroxide) variants. In: Journal of Organic Chemistry. 1994 ; Vol. 59, No. 15. pp. 4272-4280.
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