Planar cationic systems as charge-transfer acceptors

✍ Scribed by Martin Feldman; S. Winstein

• Publisher: Elsevier Science
• Year: 1962
• Tongue: French
• Weight: 216 KB
• Volume: 3
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)71734-5

✦ Synopsis

THE tropylium ion I is an, interesting acceptor in charge-transfer complex formation, and we recently reported the formation of such complexes with aromatic hydrocarbons.

2 For tropylium iodide a charge-transfer band at 575 m in methylene chloride has been observed by Harmon and coworkers.3

In comparing tropylium ion with other planar cationic acceptors, we have now also employed iodide ion as the donor, since it has a relatively low ionization potential and its own absorption occurs at low wavelength relative to that of its complexes.

Pyrylium ions have a r-electron system isoelectronic with that of tropylium ion, and we have now compared 2,4,6_trimethylpyrylium II with tropylium in charge-transfer complex formation. 4 The iodide was prepared from the corresponding perchlorate by ion exchange employing Dowex 2-X8 resin in the iodide form. The yellow salt, m.p. ca. 200' (dec.), may be recrystallized from glacial acetic acid and it can be titrated with aqueous silver nitrate (Found, 50.5; talc. $ I ', 50.8). The 2,4,6_trimethylpyrylium io-N.S.F. Predoctoral Fellow, 1958-1962.