VOLTAMMETRIC STUDY OF THE OXIDATION OF METAL DERIVATIVES OF BUCKMINSTERFULLERENE (C-60)

The oxidation of the following derivatives has been studied by cyclic voltammetry in tetrahydrofuran solvent at a platinum electrode: (Et(3) P)(2)M(eta(2)-C-60, [(Et(3)P)(2)M]C-6(60)) (M = Pt, Pd, Ni; Et = ethyl ) and [(Et(3)P)(2)Pt]C-n(60) (n = 2-4). The derivatives containing one organometallic group are oxidized in a two-electron irreversible reac tion that cleaves off the metal fragment giving free C-60. As addition al platinum-containing groups are added in the series [(Et(3)P)(2)Pt]C -n(60) (n = 1-4), the complexes become successively more easily oxidiz ed. For n = 2 and n = 3, the first step of oxidation involves cleavage of the addend giving the next lower complex until, at the most positi ve peak, C-60 is produced. For [(Et(3)P)(2)Pt]C-4(60), the first step of oxidation is a one-electron process that shows some chemical revers ibility. A second irreversible step may represent a second step of oxi dation or be due to a different isomer. The previously reported anodic peak potentials for the complexes n = 1-6, M = Pt, Pd, Ni, vary linea rly with n. The sensitivity of the peak potentials to the number of ad dends is discussed with reference to similar effects seen for the reve rsible reduction potentials.