The carboxylato–Cu(II) complexes of type [Cu2(RCOO)4] and their benzothiazole adducts [Cu2(RCOO)4bt2] (bt = benzothiazole, R = CH3(CH2)n−2, n = 12, 14, 16, 18) form the main objectives of this study. The studied carboxylato–Cu(II) complexes are formed from dimeric
units to polymeric chains (chromofor CuO5). The structural changes are due to coordination of ligand (benzothiazole). The polymeric chains of carboxylato–Cu(II) complexes
degraded to discrete centrosymetric tetracarboxylate-bridged dimmers (chromofor CuO4N). These prepared compounds [Cu2(RCOO)4] and [Cu2(RCOO)4L2] were submitted to measurements relating to spectral (IR, UV–Vis) and thermal properties (TG, DTA, DSC).