Isolation and spectroscopic characterization of Sm-containing metallofullerenes

We report the first isolation of a series of Sm-containing metallofullerene s, Sm@C-74, Sm@C-76(I,II), Sm@C-78, Sm@C-80, Sm@C-82(I,II,III) and Sm@C-84( I,II,III), and their characterization by UV-VIS-NIR absorption spectroscopy and electron energy-loss spectroscopy (EELS). The UV-VIS-NIR absorption sp ectra of Sm@C-74, Sm@C-80, Sm@C-82(I, II, III) and Sm@C-84(I,II) are quite similar to those of the corresponding Ca-, Sr-, Ba-, Eu-, Tm-, Yb-based met allofullerenes. In contrast, the absorption spectra of Sm@C-76(I, II), Sm@C -78 and Sm@C-84(III) show a novel feature: the onset for Sm@C-78 is observe d similar to 2600 nm, which corresponds to a small band gap (similar to 0.5 eV). Furthermore, the oxidation state of Sm atom in Sm@C-82(II) is investi gated by EELS, which reveals that the Sm atom takes +2 oxidation state in t his fullerene cage. (C) 2000 Elsevier Science B.V. All rights reserved.