Isolation and characterisation of forty-nine fluorinated derivatives of [70]fullerene

Abstract

From 100 mg of the product of fluorination of [70]fullerene with MnF₃ at 450 °C at ca. 0.1 bar, we have isolated forty-nine components by HPLC and characterised them by mass spectrometry, together with IR and both 1D and 2D ¹⁹F NMR spectroscopy (where quantities permitted). The separation was carried out using a 4.6 mm diameter Cosmosil ‘Buckyprep’ column with elution by either toluene, various toluene–heptane mixtures, or heptane, and entailed some 950 manual runs. The products comprise numerous isomers of C₇₀F₄₄, C₇₀F₄₂, C₇₀F₄₀, C₇₀F₃₈, C₇₀F₃₆, C₇₀F₃₄, C₇₀F₄₀O, C₇₀F₃₈O, C₇₀F₃₆O, C₇₀F₃₆O₂, C₇₀F₃₅O·OH, C₇₀F₃₇·O·OH, and C₇₀F₃₄O₃. A component that eluted just before one of the C₇₀F₃₈ isomers, was indicated by mass spectrometry to be C₇₀F₃₇ but is probably an exceptionally stable fragment produced by degradation of an oxide precursor, a view supported by temperature-degradation studies. One each of C₇₀F₄₂, C₇₀F₃₈, C₇₀F₃₆ isomers, at least two C₇₀F₄₀ isomers, and C₇₀F₃₄O₃ have either C_s or C₂ symmetry, all the other compounds have C₁ symmetry. The main components are two C₇₀F₃₈ isomers (nos. 8 and 14). Other components detected in trace amounts were C₇₀F₃₉O·OH, the poly-epoxides C₇₀F₃₆O, C₇₀F₃₆O₂ and C₇₀F₃₆O₃ and the poly-epoxy dihydroxides, C₇₀F₃₀O₂(OH)₂, C₇₀F₃₀O₃(OH)₂, and C₇₀F₃₀O₄(OH)₂.