Spin-Carrying Benzoquinone Derivatives

• Published in: Journal of organic chemistry 2009-12, Vol.74 (24), p.9345-9350
• Main Authors: Nakatsuji, Shin’ichi, Nobusawa, Mitsunori, Suzuki, Hideto, Akutsu, Hiroki, Yamada, Jun-ichi
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; Free radicals chemistry; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Noncondensed benzenic compounds; Organic chemistry; Preparations and properties; Reactivity and mechanisms
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo902007m

Several 1,4-benzoquinone derivatives carrying oxy-TEMPO radical(s) at the 2-position or 2,5-positions were found to give black crystals by recrystallization from pale yellow solutions and it was revealed from their crystal structures that unusual single-component CT complexes were formed, in which a nitroxide moiety plays the roll of a donor part and a 1,4-benzoquinone group of the same molecule works as an acceptor part, respectively. On the contrary, no CT formation was found for the derivatives carrying oxy-TEMPO radicals at 2,6-positions and one of the TEMPO groups contributes to a CT formation in a 1,4-benzoquinone derivative carrying amino-TEMPO radicals at 2,5-positions derived from fluoranil, while the other one has a close oxygen-to-oxygen contact with another neighboring molecule to give a very large exchange coupling of J/k B = −154 K.