Resonant low energy electron attachment to SF6 and C6F6 in argon clusters and on a multilayer krypton film is presented. The energy dependence of the absolute attachment cross sections for the condensed molecules is determined in the range 0-8 eV by measuring charge localization on the film. We find a cross section maximum of (3.0 +/- 0.8)x10(-15) cm(2) at 60 meV for SF6- formation, which is close to the gas phase value. For C6F6, we obtain a maximum value (4.8 +/- 1.2)x10(-15) cm(2) at 75 meV. In contrast to isolated gas phase molecules, where both ions are only observed in a very narrow energy range around 0 eV, SF6- resulting from electron attachment to clusters is observed up to 1.5 eV. The same is true for the condensed submonolayers, where charge localization is observed up to 1.5 eV for SF6. The extension of stable SF6- formation to much higher energies in condensed media is attributed to the transfer of intramolecular vibrational energy from SF6- to phonon vibrational modes of the Ar cluster or the Kr multilayer film. C6F6- formation is also observed up to 1.7 eV from clusters, but on the film, charge localization is only detected up to 0.7 eV. This difference is explained by the orientation of the C6F6 molecules on the rare gas film, which diminishes vibrational energy transfer to the phonon bath of the Kr lattice. Similar results are also obtained for the dimeric configurations of these molecules seeded into Ar clusters.