Perfluoromethyl and perfluoroethyl groups exhibit comparable electron-withdrawing properties. Due to their different steric demand, however, a distinct difference in the reactivity of the corresponding perfluoroalkylated compounds may result.         Tolman published a cone angle of 137� for the P(CF3)3 ligand [1], which is increased up to 191� (gas phase) for the perfluoroethyl homologue P(C2F5)3 [2]. This explains the lower coordination properties of P(C2F5)3 as compared to the slimmer P(CF3)3.         Besides the different steric demand perfluoromethyl and perfluoroethyl compounds exhibit a significantly different carbene elimination tendency. This results in a drastically different thermal stability of perfluoromethyl- and perfluoroethyl element compounds. While LiCF3 and F3SiCF3, for example, readily eliminate difluorocarbene, the corresponding perfluoroethyl derivatives LiC2F5 and F3SiC2F5 exhibit distinctive higher decomposition temperatures [3, 4].         The carbene elimination tendency also influences the sensitivity towards air. While P(CF3)3 reacts violently on contact with air [5], the less volatile homologue P(C2F5)3 can be handled by standard Schlenk techniques.Within this contribution we will present the synthesis and properties of novel bis- and tris(perfluoroethyl)element compounds. References1) For example: C. A. Tolman, Chem. Rev., 77 , 313, (1977).2) S. A. Hayes, R. J. F. Berger, B. Neumann, N. W. Mitzel, J. Bader, B. Hoge, Dalton Trans., 39 , 5630 (2010).3) M. H. K�nigsmann, Dissertation, Universit�t Bremen, Bremen, (2005).4) K. G. Sharp, T. D. Coyle, Inorg. Chem., 11 , 1259 (1972).5) W. Mahler, Inorg. Chem., 18 , 352 (1979).

About the different reactivity of perfluoromethyl and perfluoroethyl compounds

248th National Meeting (2014)

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