@article{217ae9bae302454595ed057924bae1be,
title = "Mono- and dianion of benzoquinone-linked [60]fullerene",
abstract = "Reduction of the benzoquinone-linked [60]fullerene first gives the moroanion containing the semiquinone-radical and C60-moieties. The further reduction of the monoanion produces the dianion containing the semiquinone-radical and C60-anion moieties. The EPR spectra of the dianion clearly show the triplet interaction between the semiquinone and C60 radical anions.",
author = "Masahiko Iyoda and Shigeru Sasaki and Fatema Sultana and Masato Yoshida and Yoshiyuki Kuwatani and Shigeru Nagase",
note = "Funding Information: At first, the reduction of 9 by potassium mirror was monitored by EPR. The spectrum of 10 in THF shows a single signal (g 2.000, AHpp = I .3 Ci at 292 K; g 2.000, AHpp = 5 I G at 5.7 K). which follows the Curie law in the range 5.9-129 K with g value and AHpp constant. Therefore, the monoanion 10 can be regarded as a Cm anion radical, although the linewidth narrowing at lower temperature typical of the C6u anion radical is not observed.r2 A similar reduction of 1 with potassium in THF gives the EPR spectra of the dianion 3*2K+, which consists of a broad signal at the center and a fine structure due to triplet species (g 2.002, D = 45.8 G) at 77 K (Fig. 2a).13 Both signals obey the Curie law over the range 16-120 K without change in the spectrum, although the Am, = 2 signals were not observed. The THF solution of 3*2K+ at 293 K shows a spectrum with an unresolved structure (Fig. 2b), which gradually changes to a more simple one composed of a semiquinone radical anion (g 2.005, aB = 2.1 G (6H)) and a fullerene radical anion (g 2.000, AHpp = I .4 G), presumably due to the disappearance of the dianion, although some monoanionic species (2 and the degradation products of 2 and 3) remain in the solution. The sodium reduction of 1 in THF gives almost the same results as potassium (g 2.001, D = 46.0 G at 77K) (Fig. 2c) without any counter cation dependence as known in semiquinone radical anionsI The solution of 3*2Na+ is more stable than that of 3*2K+ and remains unchanged at 293 K. The distance between two spins estimated from D value by the point dipole approximation (8.5 A) is comparative to the size of 1 (ca. 8.7 x 14.6 A). Thus, our results show a marked dipole-dipole interaction between the fullerene core and its substituent at the ground state. Acknowledgment. We would like to thank Professor Jun Yamauchi, Kyoto University for his helpful discussions. Financial support for this study was provided by a Grant-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Science and Culture, Japan (06224223). References and Notes I a) A. F. Hebard, M. J. Rosseinsky, R. C. Haddon, D. W. Murphy. S. H. Glarum, T. T. M. Palstre, A. P. Ramirez, A. R. Kortan, Nuture, 1991,350, 600-601; b) P.-M. Allemand, K. C. Khemani, A.",
year = "1996",
month = oct,
day = "28",
doi = "10.1016/0040-4039(96)01789-3",
language = "English",
volume = "37",
pages = "7987--7990",
journal = "Tetrahedron Letters",
issn = "0040-4039",
publisher = "Elsevier Limited",
number = "44",
}