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The room temperature reaction of C6F6 or C6F5H with [Ru(IEt2Me2)2(PPh3)2H¬2] (1; IEt2Me2 = 1,3-diethyl-4,5-dimethylimidazol-2-ylidene) generated a mixture of the trans-hydride fluoride complex [Ru(IEt2Me2)2(PPh3)2HF] (2) and the bis-carbene pentafluorophenyl species [Ru(IEt2Me2)2(PPh3)(C6F5)H] (3). The formation of 3 resulted from C-H activation of C6F5H (formed from C6F6 via stoichiometric hydrodefluorination), a process which could be reversed by working under 4 atm H2. Upon heating 1 with C6F5H, the bis-phosphine derivative [Ru(IEt2Me2)(PPh3)2(C6F5)H] (4) was isolated. A more efficient route to 2 involved treatment of 1 with 0.33 eq of TREAT-HF (Et3N·3HF); excess reagent gave instead the [H2F3]- salt (5) of the known cation [Ru(IEt2Me2)2(PPh3)2H]+. Under catalytic conditions, 1 proved to be an active precursor for hydrodefluorination, converting C6F6 to a mixture of tri, di and monofluorobenzenes (TON = 37) at 363 K with 10 mol% 1 and Et3SiH as the reductant.
Cybulski, M. K., Riddlestone, I. M., Mahon, M. F., Woodman, T. J., & Whittlesey, M. K. (2015). Stoichiometric and catalytic C-F bond activation by the trans-dihydride complex [Ru(IEt2Me2)2(PPh3)2H2] (IEt2Me2 = 1,3-diethyl-4,5-dimethylimidazol-2-ylidene). Dalton Transactions , 44(45), 19597-19605. https://doi.org/10.1039/C5DT01996F