Abstract The 20-membered N3O2-macrocycle L reacts with copper(II) salts (NO3, ClO4) in dichloromethane/methanol to yield unexpected isostructural chloro-bridged dinuclear bis(macrocycle) copper(II) complexes of type [LCuII-(μ-Cl)2-CuIIL]X2 (1: X = NO3, 2: X = ClO4). Each complex contains two five-coordinate copper(II) ions which are bridged by two chloro-ligands, (μ-Cl)2, and the remaining coordination sites are completed by three nitrogens from the macrocycle. Notably, the chloro-bridging ligands are derived from the partial decomposition of the dichloromethane solvent molecules. Analogous reaction employing copper(I) chloride also afforded a similar dimer complex, [LCuII-(μ-Cl)2-CuIIL]Cl2 (3), suggesting such type of the chloro-bridged dicopper(II) complexes are thermodynamically stable under the reaction conditions employed in this work. Considering the τ values (0.45–0.52) for the five-coordinated copper(II) centers, complexes 1–3 present an intermediate geometry between square planar and trigonal bipyramidal arrangements.