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(diphenylphosphi no)propane). An X-ray investigation of la shows a distorted trigonal bipyra midal 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 L igand is only slightly higher than that of chloride. The reaction of 1a wit h [Me4N]F gives cis-[RuF2(dppp)(2)] (3), a rare difluoro complex not stabil ized by pi-acidic co-ligands. The Ru-F bond of 1a is hydrogenolyzed upon re action with Hz to give [RuH(eta(2)-H-2)(dppp)2](+) The coordinatively unsat urated 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 wit h (E)-3-bromo-1,3-diphenylpropene and chlorotriphenylmethane. Substrate con version decreases with decreasing substitution at the halogen-bearing carbo n atom.