Novel 1D and 2D heterometallic Cu/Cd complexes comprising unique mixed-anion Cd(μ-Cl)(μ-O2CMe)Cl(O2CMe)2−, Cd(μ-O2CMe)2I(O2CMe)2−, Cd(μ-I)(μ-O2CMe)I(O2CMe)2− and Cd2(NCS)6(O2CMe)22- building blocks: Synthesis from elemental copper, structure and magnetism