C-F Bond Activation of P(CF) by Ruthenium Dihydride Complexes: Isolation and Reactivity of the "Missing" Ru(PPh)H(halide) Complex, Ru(PPh)HF.

The major product of the reaction between Ru(IMe)(PPh)H (1; IMe = 1,3,4,5-tetramethylimidazol-2-ylidene) and P(CF) (PCF) is the five-coordinate complex Ru(IMe)(PF{CF})(CF)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(PPh)H to afford Ru(PPh)HF (3). NaBAr abstracted the fluoride ligand in 3 to give [Ru({η-CH}PPh)(PPh)H][BAr], while Bpin reacted with 3 in CD to yield a mixture of [Ru({η-CD)(PPh)H] and Ru(PPh)H. The treatment of 3 with HBpin (5 equiv) and HSiR (R = Et, Ph; 2 equiv) afforded Ru(PPh)(σ-HBpin)H and Ru(PPh)(SiR)H, respectively. No stable substitution products were generated when 3 was reacted with MeSiX (X = CF, CF).