Octafluorocubane or perfluorocubane is an organofluorine compound with the formula C8F8, consisting of eight carbon atoms joined into a cube, with a fluorine bonded to each carbon corner. It is a colorless, sublimable solid at room temperature. It has been of longstanding theoretical interest, but was not synthesised until 2022, when it was prepared in several steps from the (CF3)2CFCH(OH)C2F5 ester of carboxycubane, beginning with its heptafluorination. According to X-ray crystallography, the C–C distances (1.570 Å) in octafluorocubane are consistent in length with those in the parent cubane (1.572 Å). Octafluorocubane has attracted interest from theorists because of its unusual electronic structure, which is indicated by its susceptibility to undergo reduction at −2.1 V to a detectable (though unstable) anion C8F−8, with the free electron trapped inside of the cube. Octafluorocubane crystals exhibit intermolecular σ-hole interactions between fluorine atoms and neighboring cyclobutane ring centers. The molecule is predicted to be a strong tetrel bond donor. It was voted "favorite molecule of 2022" by readers of Chemical & Engineering News.
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