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Scientific article
English

On the synthesis and optical properties of sulfur-bridged analogues of triangulenium cations and their precursors

Published inJournal of physical organic chemistry, vol. 23, no. 11, p. 1049-1056
Publication date2010
Abstract

Several sulfur-bridged heterocyclic carbocations of the acridinium and triangulenium family were prepared using 9-(2,6-dimethoxyphenyl)-1,8-dimethoxy-thioxanthenium tetrafluoroborate [7][BF4] as key synthetic intermediate. Thanks to simple yet not so facile aromatic nucleophilic substitution reactions, thiachromenoacridinium, azaoxa- and dioxathiotriangulenium salts (e.g., [8][BF4], [9][BF4], and [10][BF4], respectively) were obtained in moderate to good yields. Importantly, from the crystal structural analysis of 9-(2,6-dimethoxyphenyl)-1,8-dimethoxy-9H-thioxanthen-9-ol 16, bond lengths between sulfur and carbon atoms were confirmed to be much longer than that of classical CO or CN in analogous frameworks. This clearly triggers a distortion of the sulfur-containing six-membered ring which can be invoked to explain the relative lack of stabilization of the resulting carbenium ions. The increased electrophilicity of the central carbon set off a strongly reduced reactivity towards SNAr reactions. A comparison between electronic absorption spectra of the sulfur-bridged dyes and their aza analogues was also carried out. A ca. 50 nm shift towards the low energy region was found to occur upon the insertion of the sulfur atom. Copyright © 2010 John Wiley & Sons, Ltd.

Keywords
  • Angulenium
  • Sulfur
  • Synthesis
Citation (ISO format)
NICOLAS, Cyril, BERNARDINELLI, Gérald Hugues, LACOUR, Jérôme. On the synthesis and optical properties of sulfur-bridged analogues of triangulenium cations and their precursors. In: Journal of physical organic chemistry, 2010, vol. 23, n° 11, p. 1049–1056. doi: 10.1002/poc.1753
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ISSN of the journal0894-3230
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