Cyclic dimers of tetrafluorobutatriene

Abstract

1,1,4,4-Tetrafluorobutatriene polymerizes even at -78 °C within a short time yielding a red insoluble polymer. Possible closed-shell cyclic dimers and oligomers resulting from several reaction paths were analyzed by computational methods-with CCSDT/cc-pVTZ as the highest order calculation and several other calculations of lower level. For a better understanding of fluorination effects, the perhydrogen triene dimers were included in this study. The destabilization of the central cumulenic double bond of tetrafluorobutatriene relative to ethylene and the further destabilizing fluorine substitution makes the formation of most of the dimers exothermic with only one exception for the perfluoro derivatives. Astonishingly, the geometry of some of the discussed molecules is highly affected by fluorine substitution, while for others there is nearly no effect on the geometry of the carbon backbone. 19F-NMR shifts of the potential dimers were calculated using the GIAO method. © 2011 Springer-Verlag.