Electronic Structures of Novel Tetrasilyl-Substituted Ethylenes: 5,5,6,6,11,11,12,12-Octaethyl-5,6,11,12-tetrasilanaphthacene and 1,1′-Bis(3,4-benzo-2,2,5,5-tetraethyl-2,5-disilacyclopent-3-enylidene)

Kazuyoshi Tanaka, Takao Yoshii, Akihiro Ito, Mitsuo Ishikawa, Akinobu Naka, Mamoru Fujitsuka, Akira Watanabe, Osamu Ito, Yoichi Matsuzaki

Research output: Contribution to journalArticlepeer-review

Abstract

Electronic structures of the two structural isomers of novel tetrasilyl-substituted ethylenes, 5,5,6,6,11,11,12,12-octaethyl-5,6,11,12-tetrasilanaphthacene (1) and 1,1′-bis(3,4-benzo-2,2,5,5-tetraethyl-2,5-disilacyclopent3-enylidene) (2), were studied from the viewpoint of electronic effect occurring from geometrical difference in the vicinity of the tetrasilylethene moiety. Characteristic weak bands at 350 (1) and 403 (2) nm of the absorption spectra in solution were attributed to the φ(HOMO) → π* (LUMO) transition on the basis of the quantum chemical configuration interaction (CI) calculations by the semiempirical INDO/S model and ab initio Hartree - Fock theory. Moreover, the large bathochromic shift of 53 nm between 1 and 2 could be ascribed to the raising of the HOMO of 2, as is supported by cyclic voltammetry measurements: the small Si-C-Si bond angle of the tetrasilylethene moiety destabilizes the HOMO energy of 2 compared with that of 1.

Original languageEnglish
Pages (from-to)1126-1131
Number of pages6
JournalJournal of Physical Chemistry A
Volume103
Issue number8
DOIs
Publication statusPublished - 1999 Jan 1

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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