Toward metal-mediated C-F bond formation.: Synthesis and reactivity of the 16-electron fluoro complex [RuF(dppp)2]PF6 (dppp=1,3-bis(diphenylphosphino)propane)

The five-coordinate fluoro complex [RuF(dppp)(2)]PF6 (1a) has been prepared by reacting [RuCl(dppp)(2)]PFG (1b) with TlF (dppp 1,3-bis(diphenylphosphino)propane). An X-ray investigation of la shows a distorted trigonal bipyramidal geometry (Y-shaped). The 16-electron complex 1a reacts with a number of donors, including CO, H-2, and F-. The X-ray structure of trans-[RuF(CO)(dppp)(2)]PF6 (2aBPh(4)) suggests that the pi-donor ability of the fluoro Ligand is only slightly higher than that of chloride. The reaction of 1a with [Me4N]F gives cis-[RuF2(dppp)(2)] (3), a rare difluoro complex not stabilized by pi-acidic co-ligands. The Ru-F bond of 1a is hydrogenolyzed upon reaction with Hz to give [RuH(eta(2)-H-2)(dppp)2](+) The coordinatively unsaturated complex la reacts with activated haloalkanes R-X (X = Cl or Br) in 1:1 molar ratio to give the fluorinated organic derivative and [RuX(dppp)(2)](+). The halide metathesis proceeds instantaneously and quantitatively with (E)-3-bromo-1,3-diphenylpropene and chlorotriphenylmethane. Substrate conversion decreases with decreasing substitution at the halogen-bearing carbon atom.