Preparation, Structural Determination, and Characterization of Electronic Properties of Bis-silylated and Bis-germylated Lu3 N@Ih -C80.

Masahiro Kako, Kyosuke Miyabe, Kumiko Sato, Mitsuaki Suzuki, Naomi Mizorogi, Wei-Wei Wang, Michio Yamada, Yutaka Maeda, Marilyn M Olmstead, Alan L Balch, Shigeru Nagase, Takeshi Akasaka

Index: Chemistry 21 , 16411-20, (2015)

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Abstract

Bis-silylated and bis-germylated derivatives of Lu3 N@Ih -C80 (3, 4, 5) were successfully synthesized by the photochemical addition of disiliranes 1 a, 1 b or digermirane 2, and fully characterized by spectroscopic, electrochemical, and theoretical studies. Interestingly, digermirane 2 reacts more efficiently than disiliranes 1 a and 1 b because of its good electron-donor properties and lower steric hindrance around the Ge-Ge bond. The 1,4-adduct structures of 3, 4, 5 were unequivocally established by single-crystal X-ray crystallographic analyses. The electrochemical and theoretical studies reveal that the energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the 1,4-adducts are remarkably smaller than those of Lu3 N@Ih -C80 , because the electron-donating groups effectively raise the HOMO levels. It is also observed that germyl groups are slightly more electron-donating than the silyl groups on the basis of the redox properties and the HOMO-LUMO energies of 4 and 5. Bis-silylation and bis-germylation are effective and versatile methods for tuning the electronic characteristics of endohedral metallofullerenes.© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.