Synthesis and Spectroscopic and Electrochemical Characterization of Di- and Tetrasubstituted C60 Derivatives

The synthesis and electrochemical and spectroscopic characterization of fullerene derivatives of the type R 2 C 60 where R = C 6 H 5 CH 2, 2-BrC 6 H 4 CH 2, 3-BrC 6 H 4 CH 2, or 4-BrC 6 H 4 CH 2 and R 4 C 60 where R = C 6 H 5 CH 2 are reported. The first step in the synthesis involves an electron transfer between C 60 2- and RBr, and a similar initial electron-transfer step occurs between [(C 6 H 5 CH 2 ) 2 C 60 ] 2- and C 6 H 5 CH 2 Br during the synthesis of (C 6 H 5 CH 2 ) 4 C 60 . On the basis of NMR and UV−visible data, the investigated R 2 C 60 derivatives are identified as 1,4-adducts of C 60,whereas the isolated isomer of (C 6 H 5 CH 2 ) 4 C 60 is characterized as possessing C 1 symmetry with the four benzyl groups being close to each other. The electrochemistry of each synthesized compound was determined in benzonitrile containing 0.1 M tetra- n -butylammonium perchlorate and each mono- and dianion of R 2 C 60 and R 4 C 60 were characterized by near-infrared spectroscopy. The near-infrared spectra of each species show two major “marker bands” which can be considered to be diagnostic of the fullerene derivative oxidation state.