Preparation and characterization of dinuclear copper–indomethacin anti-inflammatory drugs

The crystal and molecular structures of the ternary copper–indomethacin complexes [Cu2(Indo)4L2] (IndoH=indomethacin=1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid; L=acetonitrile (AN), N,N-dimethylacetamide (DMA), tetrahydrofuran (THF), or pyridine (Py)) are reported. All four complexes contain a dinuclear ‘Cu-acetate’ molecular structure in which the carboxyl groups of the indomethacin ligands act as bridges. The CuCu distances of 2.649(3), 2.6240(8), and 2.6784(8) Å; CuO(Ac)av distances of 1.964, 1.970, and 1.967 Å; and CuL distances of 2.132(6), 2.1805(17), and 2.177(2) Å, respectively, for L=DMA, THF and Py, are typical of such distances in dinuclear complexes of this type. There are two independent complexes in the AN adduct with CuCu distances of 2.6311(11) and 2.6206(8) Å; CuO(Ac)av distances of 1.965 and 1.965 Å; and CuLav distances of 2.184 and 2.197 Å, respectively. The pyridine complex exists mainly as a monomer in solution, which may be associated with the longer CuCu bond in this adduct as compared to the other complexes.