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Published on: July 28, 2022
Radical site-dependent exchange interactions in acridane-based bisnitroxides
Yuta Takenouchi1, Takuya Kanetomo1, Masaya Enomoto1
1Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan. kanetomo@rs.tus.ac.jp.
Abstract:
To investigate the radical site-dependence of exchange coupling in bisnitroxides, we have synthesized novel three acridane-based diradicals, tert-butyl nitroxide groups at the 2,7-, 2,6- and 3,6-positions of 10-benzyl-10'-methyl-9,9'(10H,10'H)spirobiacridine (1-pp, 1-mp and 1-mm, respectively). Theoretical and experimental magnetic studies indicate that 1-pp and 1-mm exhibit a singlet ground state, while 1-mp exhibits a triplet ground state. These spin states can be explained by the spin polarization mechanism. Quantitative analysis revealed a difference in the magnitude of the exchange coupling constants between 1-pp and 1-mm owing to their local spin structures corresponding to 1,4- and 1,3-phenylene diradical motifs (Kekulé and non-Kekulé structures, respectively).
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