Synthesis, Structure, and Function of Polyfluorocubanes

Fluorine is a unique element, characterized by the highest electronegativity, the second smallest atomic radius after hydrogen, and low polarizability. When incorporated into organic molecules, fluorine significantly modifies their structures and properties. In this work, the author and coworkers successfully introduced multiple fluorine atoms into a cubic-shaped molecule called cubane, by employing their “PERFECT method”, a liquid-phase fluorination technique using fluorine gas. The first part focuses on synthesis of perfluorocubane, which has been expected to accept an electron inside its cubic skeleton. They successfully isolated the target molecule, and demonstrated the electron acceptance in the cube. The second part is about synthesis and structural analysis of hexafluorodihalocubanes. Based on the X-ray diffraction analysis of crystal and X-ray absorption spectroscopy in solution, the C-X bond (X=Cl, Br, I) in the molecules was found to be exceptionally short. Comparing to halotrinitromethanes, which is the representative series of compounds with short C-X bond, reasons for the bond-shortening will be comprehensively discussed.