C–F Bond Activation of P(C6F5)3 by Ruthenium Dihydride Complexes: Isolation and Reactivity of the “Missing” Ru(PPh3)3H(halide) Complex, Ru(PPh3)3HF

The major product of the reaction between Ru(IMe4)2(PPh3)2H2 (1; IMe4 = 1,3,4,5-tetramethylimidazol-2-ylidene) and P(C6F5)3 (PCF) is the five-coordinate complex Ru(IMe4)2(PF2{C6F5})(C6F5)H (2), which is formed via a complex series of C–F/P–C bond cleavage and P–F bond formation steps. In contrast, hydrodefluorination of all six ortho C–F bonds in PCF occurs with Ru(PPh3)4H2 to afford Ru(PPh3)3HF (3). NaBArF4 abstracted the fluoride ligand in 3 to give [Ru({η6-C6H5}PPh2)(PPh3)2H][BArF4], while B2pin2 reacted with 3 in C6D6 to yield a mixture of [Ru({η6-C6D6)(PPh3)2H]+ and Ru(PPh3)4H2. The treatment of 3 with HBpin (5 equiv) and HSiR3 (R = Et, Ph; 2 equiv) afforded Ru(PPh3)3(σ-HBpin)H2 and Ru(PPh3)3(SiR3)3H3, respectively. No stable substitution products were generated when 3 was reacted with Me3SiX (X = CF3, C6F5).