Perfluoro-1,1 '-biphenyl and perfluoronaphthalene and their derivatives as pi-acceptors for anions

Addition of anions to perfluorinated 1,1'-biphenyl 1 or naphthalene 2 results in a shift of the F-19 NMR signals. However, any specific interaction cannot be assigned to this effect. In order to study the interaction in more detail, the salt derivatives 3 and 4 were prepared and studied by single crystal X-ray diffraction revealing weak anion-pi interactions in the solid state.