Electrochemical Studies of Three Disamarium Large Metallofullerenes Sm2@D2(35)-C88, Sm2@C1(21)-C92 and Sm2@D3d(822)-C104

We isolated and purified three disamarium metallofullerenes of known structure, Sm 2 @ D 2 (35)-C 88 , Sm 2 @ C 1 (21)-C 92 and Sm 2 @ D 3d (822)-C 104 , by the reported method. Importantly, we characterized these three di-samarium metallofullerenes by cyclic voltammetry and differential pulse voltammetry, which is the first report of electrochemical studies of di-metallofullerenes containing divalent metal atoms. Their oxidation reactions are observed at a maximum positive potential compared with other endohedral metallofullerenes (EMFs), which, other than those of mono-samarium metallofullerenes, have never been reported. The electrochemical studies of these three compounds show much weaker electron-donating capacity and stronger electron-accepting capacity compared with the corresponding Sm-EMFs, fullerenes, or cluster-metallofullerenes. Interestingly, further analysis shows that normal-metallofullerenes present narrower electrochemical potential gaps than cluster-metallofullerenes, which might be attributed to their stronger interaction between the inner metal ions and the carbon cage.