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

Mary A. Mackey, University of Southern Mississippi
Curtis E. Coumbe, University of Southern Mississippi
David T. Heaps, University of Southern Mississippi
Bridget S. Confait, University of Southern Mississippi

Abstract

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.