Perchlorinated derivatives of the common o-diimine chelate ligands 2,2′-bipyridine and 1,10- phenanthroline were synthesized and tested for their coordination behavior towards metal ions. Octachloro-1,10-phenanthroline (ocp) was obtained via chlorination with PCl 5 under pressure (300 ° C, 18 h). It fails to form stable complexes with e.g. Fe 2+ , Mn 2+ , Ru 2+ , Ni 2+ . Zn 2+ or Cd 2+ , but yields complex cations [M(ocp) 2 ] + with M = Cu, Ag. The crystal structure analysis of the red tetrafluoroborate of the copper(I) complex cation reveals a distorted tetrahedral coordination at the metal with a slight tendency towards the trigonal-pyramidal arrangement; two essentially planar ligands with small bite angles intersect at almost right angle. Relative to conventional bis(1,10-phenanthroline)copper(I) complexes with similar structures. [Cu(ocp) 2 ] + has oxidation and reduction potentials shifted positively by about 1 V which leaves the energy of the main MLCT absorption features little changed. Attempts to synthesize RuCl 2 (ocp) 2 in DMF produced as substituted product a symmetrical bis(dimethylamino)-hexachloro-1,10-phenanthroline which can be oxidized electrochemically in two steps. In contrast to ocp, octachloro-2,2′-bipyridine (ocb) showed no detectable complexation with Cu + and a very negative reduction potential, most probably due to its inability to exhibit a low-energy coplanar conformation.