Photochemistry of the π-Extended 9,10-Bis(1,3-dithiol-2-ylidene)- 9,10-dihydroanthracene System: Generation and Characterisation of the Radical Cation, Dication, and Derived Products

✍ Scribed by Allison E. Jones; Christian A. Christensen; Dmitrii F. Perepichka; Andrei S. Batsanov; Andrew Beeby; Paul J. Low; Martin R. Bryce; Anthony W. Parker

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 146 KB
• Volume: 7
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/1521-3765(20010302)7:5<973::aid-chem973>3.0.co;2-#

✦ Synopsis

Flash photolysis of bis [4,5di(methylsulfanyl)1,3-dithiol-2-ylidene]-9,10-dihydroanthracene (1) in chloroform leads to formation of the transient radical cation species 1 . which has a diagnostic broad absorption band at l max % 650 nm. This band decays to half its original intensity over a period of about 80 ms. Species 1 . has also been characterised by resonance Raman spectroscopy. In degassed solution 1 . dis-proportionates to give the dication 1 2 , whereas in aerated solutions the photodegradation product is the 10-[4,5-di-(methylsulfanyl)1,3-dithiol-2-ylidene]anthracene-9(10 H)one (2). The dication 1 2 has been characterised by a spec-troelectrochemical study [l max (CH 2 Cl 2 ) 377, 392, 419, 479 nm] and by an X-ray crystal structure of the salt 1 2 (ClO 4 À ) 2 , which was obtained by electrocrystallisation. The planar anthracene and 1,3-dithiolium rings in the dication form a dihedral angle of 77.28; this conformation is strikingly different from the saddle-shaped structure of neutral 1 reported previously.