Effect of addition pattern on the electrochemical and spectroscopic properties of neutral and reduced 1,2-and 1,4-(C6H5CH2)2C60 isomers

The spectral and electrochemical properties of isomeric 1,2- and 1,4-adducts of fullerenes of the type R2C60 have been examined in their neutral, singly and/or doubly reduced forms. The first reduction potentials of 1,2- and 1,4-(C6H5CH2)(2)C-60 in PhCN containing 0.1 M TBAP are the same within experimental error but the second and third reductions of the two isomers differ by 50 mV, with the 1,2-isomer being easier to reduce. Much larger differences, however, are seen in the near-IR spectra of the singly and doubly reduced organofullerene isomers. The monoanion of 1,2-R2C60 possesses an absorption band at about 1000 nm, while the dianion has a band at around 900 nm, The 1,4-R2C60 derivatives also show bands at similar wavelengths in their monoanionic and dianionic forms, but there is a second near-IR band at 1500 (monoanion) or 1300 nm (dianion).