Mechanistic studies of the rhodium NHC catalyzed hydrodefluorination of polyfluorotoluenes

Leonid Schwartsburd, Mary F. Mahon, Rebecca C. Poulten, Mark R. Warren, Michael K. Whittlesey

OAI: oai:purehost.bath.ac.uk:openaire_cris_publications/28fb44ce-263b-4b28-97b2-da4e489f8baa • DOI: https://doi.org/10.1021/om500827d

The six-membered-ring NHC complexes Rh(6-NHC)(PPh₃)₂H (6-NHC = 6-ⁱPr (1), 6-Et (2), 6-Me (3)) have been employed in the catalytic hydrodefluorination (HDF) of C₆F₅CF₃ and 2-C₆F₄HCF₃. Stoichiometric studies showed that 1 reacted with C₆F₅CF₃ at room temperature to afford cis- and trans-phosphine isomers of Rh(6-ⁱPr)(PPh₃)₂F (4), which re-form 1 upon heating with Et₃SiH. Although up to three consecutive HDF steps prove possible with C₆F₅CF₃, the ultimate effectiveness of the catalysts is limited by their propensity to undergo C-H activation of partially fluorinated toluenes to give, for example, Rh(6-ⁱPr)(PPh₃)₂(C₆F₄CF₃) (7), which was isolated and structurally characterized.