The Bingel monoadducts of La@C82: synthesis, characterization, and electrochemistry.
The reaction of La@C82 with diethyl bromomalonate in the presence of base (the Bingel reaction) generated five monoadducts which have been fully characterized. It was found that four of them (mono-A, -B, -C, and -D) are ESR-inactive, suggesting singly bonded regioisomers. In contrast, the fifth product (mono-E) is ESR-active, indicating that it possesses a cyclic moiety between the appended malonate group and the fullerene cage, analogous to conventional Bingel adducts. The differences in the molecular structures of mono-A, -B, -C, and -E result in varying thermal stabilities and electrochemical behavior. In particular, the singly bonded monoadducts undergo the retro-Bingel reaction either under thermal treatment or during electron transfer on the cyclic voltammetric timescale. However, mono-E shows remarkable thermal stability and perfect reversibility under the same experimental conditions.
Feng
Lai
L
Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
Wakahara
Takatsugu
T
Nakahodo
Tsukasa
T
Tsuchiya
Takahiro
T
Piao
Qiuyue
Q
Maeda
Yutaka
Y
Lian
Yongfu
Y
Akasaka
Takeshi
T
Horn
Ernst
E
Yoza
Kenji
K
Kato
Tatsuhisa
T
Mizorogi
Naomi
N
Nagase
Shigeru
S