The compound 2,2,5,5-tetrafluoro-2,5-dihydrofuran (1)  has been synthesized as a candidate monomer for synthesizing amorphous fluoropolymers in our research laboratory. Meanwhile, several crystal structures of products resulting from either new or existing chemistry of this cyclic ether have been solved and will be reported herein. The structures of the tricyclic ether 4 , resulting from the photodimerization of 1 in the presence of dry air, as well as perfluorooxodiacetic acid, resulting from the ring-opening oxidation of 1 , show a variety of short H···F, F···F, and O···F interactions. The crystal structure of 1,1,2,2,3,3,4,4-octafluorobutane-1,4-disulfonyl dichloride (ODD) reveals not only short F···F contacts but also short O···Cl contacts as well. The crystal structures of disilver perfluorooxodiacetate, AgO(O)CCF2OCF2C(O)OAg, and silver pentafluorosulfanyldifluoroacetate, AgOC(O)CF2SF5, salts prepared from the corresponding acids [4,5], show both short Ag···Ag and Ag···O contacts, where the former argentophilic interactions  are as short as 2.8-3.0 Å. Finally, the crystal structures of several other pentafluorosulfanyl derivatives (substituted benzenes and heterocycles) will be discussed in terms of additional examples of short H···F, F···F, and O···F interactions.
Liu, Xiaolin; Matsnev, Andrej V.; Belina, Steven P.; McMillen, Colin D.; and Thrasher, Joseph S., "Short F···F and F(Cl)···O contacts in fluoroorganic crystals, and short Ag···Ag and Ag···O contacts in silver polyfluoroacetate salts" (2016). Chemistry Annual Research Symposium. Paper 5.