832076-26-3Relevant academic research and scientific papers
Hydrogen for fluorine exchange in C6F6 and C 6F5H by monomeric [1,3,4-(Me3C) 3C5H2]2CeH: Experimental and computational studies
Maron, Laurent,Werkema, Evan L.,Perrin, Lionel,Eisenstein, Odile,Andersen, Richard A.
, p. 279 - 292 (2005)
The net reaction of monomeric Cp′2CeH [Cp′ = 1,3,4-(Me3C)3(C5H2)] in C 6D6 with C6F6 is Cp′2-CeF, H2, and tetrafluorobenzyne. The pentafluorophenylmetallocene, Cp′2Ce(C6F 5), is formed as an intermediate that decomposes slowly to Cp′2CeF and C6F4 (tetrafluorobenzyne), and the latter is trapped by the solvent C6D6 as a [2+4] cycloadduct. In C6F5H, the final products are also Cp′2CeF and H2, which are formed from the intermediates Cp′2Ce(C6F5) and Cp′2Ce(2,3,5,6-C6F4H) and from an unidentified metallocene of cerium and the [2+4] cycloadducts of tetra- and trifluorobenzyne with C6D6. The hydride, fluoride, and pentafluorophenylmetallocenes are isolated and characterized by X-ray crystallography. DFT-(B3PW91) calculations have been used to explore the pathways leading to the observed products of the exergonic reactions. A key step is a H/F exchange reaction which transforms C6F6 and the cerium hydride into C6F5H and Cp′2CeF. This reaction starts by an η1-F-C6F5 interaction, which serves as a hook. The reaction proceeds via a σ bond metathesis where the fluorine ortho to the hook migrates toward H with a relatively low activation energy. All products observed experimentally are accommodated by pathways that involve C-F and C-H bond cleavages.
