Abstract: Free perfluorosulfonylmethide compounds and metal salts thereof show strong catalytic activity in carbon-carbon bond formation reactions, in amounts as low as 0.1 mole %. Fluorous media may be used, especially biphasic fluorous media enabling ready recycling of the catalyst. The formula thereof is: M[C(SO2R1)3−(m+q)(SO2R2)m(SO2R3)q]x where M is H, Sc, Y, La, Ce, Pr, Nd, Sm Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Hf, Th, Nb, Ta, U, Bi, Al, Ga, In or Tl, x is the common oxidation state of a said metal M, R1, R2 and R3 are perfluorinated or polyfluoronated hydrocarbon, ether or amine moieties or mixtures thereof and m+q=0, 1, 2 or 3 (m and q being zero or integers).