Shin’ichi Nakatsuji, Atsushi Takai, Kazuyoshi Nishikawa, Yukio Morimoto, Noritake Yasuoka, Kazuya Suzuki, Toshiaki Enoki and Hiroyuki Anzai
TEMPO (2,2,6,6-tetramethylpiperidinyloxy) radical 1 and its derivatives 2–5 are found to form charge-transfer complexes with some acceptors such as TCNQF4 (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) being isolated as solid substances.