The structure of the stable Pd(0) precatalyst [(1,5-cyclooctadiene)(L·Pd)2] (L = AdBrettPhos) for the Pd-catalyzed fluorination of aryl triflates has been further studied by solid state NMR and X-ray cystrallography of the analogous N-phenylmaleimide complex. The reactivity of this complex with CDCl3 to form a dearomatized complex is also presented. In addition, studies suggest that related bulky biaryl phosphine ligands form similar complexes, although the smaller ligand BrettPhos forms a monomeric [(1,5-cyclooctadiene)(L·Pd)] species instead.