Synthese neuer perfluorierter Selenocarbonylverbindungen und 1,3-Diselenetane

Abstract

Reacting Hg(SeC₂F₅)₂ with AlI₃ or (C₂H₅)₂AlI in octamethylcyclotetrasiloxane at 40-45 °C and 5∙10^-3 Torr gives trifluoromethylselenocarbonylfluoride (1). The deep purple product polymerizes at low temperatures to a white solid, which after pyrolysis leads to a mixture of 1 and cis/trans-2,4-difluoro-2,4-bis(trifluoromethyl)-1,3-diselenetane (2a, 2b). The two isomers 2a and 2b are separated by preparative gas chromatography. Reaction of Hg(SeCF₃)₂ under the same conditions provides (trifluoromethyl-seleno)selenocarbonylfluoride (3) as a byproduct of F₂CSe. Exposing to the sunlight 3 dimerizes within three days to a mixture of cis/trans-2,4-difluoro-2,4-bis(trifluoromethylseleno)-1,3-diselenetane (4a, 4b). In a [2 + 4]-cycloaddition 1 reacts with cyclopentadiene giving a mixture of two isomers of 3-fluoro-3-trifluoromethyl-2-selenabicyclo[2.2.1]hept- 5-ene (5). ¹H-, ¹⁹F-, ¹³C-, ⁷⁷Se-NMR, IR, and mass spectroscopical data are presented.