This communication describes studies of Ph-R-F (R-F = CF3 or CF2CF3) coupling at Pd complexes of general structure ((PBu3)-Bu-t)Pd-II(Ph)(R-F). The CF3 analogue participates in fast Ph-CF3 coupling (<5 min at 80 degrees C). However, the formation of side products limits the yield of this transformation as well as its translation to catalysis. DFT and experimental studies suggest that the side products derive from facile alpha-fluoride elimination at the 3-coordinate Pd-II complex. Furthermore, they show that this undesired pathway can be circumvented by changing from a CF3 to a CF2CF3 ligand. Ultimately, the insights gained from Stoichiometric studies enabled the identification of Pd(PtBu3)(2) as a catalyst for the Pd-catalyzed cross-coupling of aryl bromides with TMSCF2CF3 to afford pentafluoroethylated arenes.