Poly(perfluoroalkylation) of Metallic Nitride Fullerenes Reveals Addition-Pattern Guidelines: Synthesis and Characterization of a Family of Sc3N@C-80(CF3)(n) (n=2-16) and Their Radical Anions
A family of highly stable (poly)perfluoroalkylated metallic nitride cluster fullerenes was prepared in high-temperature reactions and characterized by spectroscopic (MS, F-19 NMR, UV-vis/NIR, ESR), structural and electro-chemical methods. For two new compounds, Sc3N@C-80(CF3)(10) and Sc3N@C-80(CF3)(12), single crystal X-ray structures are determined. Addition pattern guidelines for endohedral fullerene derivatives with bulky functional groups are formulated as a result of experimental (F-19 NMR spectroscopy and single crystal X-ray diffraction) studies and exhaustive quantum chemical calculations of the structures of Sc3N@C-80(CF3)(n) (n = 2-16). Electrochemical studies revealed that Sc3N@C-80(CF3)(n) derivatives are easier to reduce than Sc3N@C-80, the shift of E-1/2 in potentials ranging from +0.11 V (n = 2) to +0.42 V (n = 10). Stable radical anions of Sc3N@C-80(CF3)(n) were generated in solution and characterized by ESR spectroscopy, revealing their Sc-45 hyperfine structure. Facile further functionalizations via cycloadditions or radical additions were achieved for trifluoromethylated Sc3N@C-80 making them attractive versatile platforms for the design of molecular and supramolecular materials of fundamental and practical importance.