Hyperfluorination of [60]fullerene by krypton difluoride

Abstract

Mass spectroscopy of the product of [60]fullerene fluorination by KrF₂ in HF, shows the most abundant species present to be C₆₀F₄₄ and C₆₀F₄₆, cage-opened compounds with molecular formulae up to C₆₀F₇₈ are also present. Despite long exposure of the samples to air prior to analysis, oxygenated derivatives (containing one or two oxygen atoms) are present in low concentration only. The ubiquitous oxygen content of fluorofullerenes does not therefore appear to arise substantially from atmospheric contamination. The El mass spectrum differs from that obtained with F₂-fluorinated [60]fullerene in showing a greater concentration of fragmentation ions, including species of even mass; these latter may arise from cage-opened species. The ¹⁹F NMR spectrum of the product (tetrahydrofuran solution) is similar to that found with F₂-fluorinated material, and in particular shows the sharp ringlet at ca. 151 ppm, attributed previously to a symmetrical species such as C₆₀F₆₀. With aqueous methanol, significant reaction does not occur, in marked contrast to the behaviour of fluorine-gas fluorinated [60]fullerene; possible reasons for this difference are considered.