From reactions of bis(polyfluorophenyl)ytterbium compounds R2Yb (R = C6F5or p-HC6F4) with trans-Rh(CO)Cl(PPh3)2, NiCl2(bpy) (bpy = 2,2’-bipyridyl), NiCl2(PPh3)2, PtCl2(bpy), triphenyltin chloride, iodine and mercuric chloride, the polyfluorophenyl derivatives trans-RRh(CO)(PPh3)2, R2Ni(bpy), trans-(C6F5)2Ni(PPh3)2, (C6F5)2Pt(bpy), Ph3SnC6F5, C6F5I and (C6F5)2Hg have been obtained. Reduction to mercury metal accompanied formation of the last compound. Carbonation of (C6F5)2Yb in tetrahydrofuran followed by acidification yields pentafluorobenzoic acid and, surprisingly, a significant amount of 2,3,4,5-tetrafluorobenzoic acid, in which the aromatic hydrogen is substantially derived from tetrahydrofuran. Reaction of (C6F5)2Yb with pentafluorobenzoic acid followed by acidification also gives 2,3,4,5-tetrafluorobenzoic acid. Fluoride elimination is less extensive and less specific in a similar reaction of YbI2.