Anti-Inflammatory Dinuclear Copper(II) Complexes with Indomethacin. Synthesis, Magnetism and EPR Spectroscopy. Crystal Structure of the N,N-Dimethylformamide Adduct.

Veterinary anti-inflammatory Cu(II) complexes of indomethacin (1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid = IndoH), of the general formula [Cu2(Indo)4L2] (L = N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methylpyrrolidone (NMP), and water), were studied by zero-field and X-band EPR spectroscopies, electronic spectroscopy, magnetic measurements, and X-ray powder diffraction. The complexes are similar to Cu(II) acetate monohydrate, with a strong antiferromagnetic exchange interaction, J, ranging from −141 to −152 cm-1. Variable temperature magnetic susceptibility data for all of the complexes are similar, with the exception of a [Cu2(Indo)4(H2O)2] complex, which displays an unusual increase in magnetic moment with decreasing temperature from 50 to 10 K. The X-ray powder diffraction patterns of the DMF and DMA dimers show that they are isostructural. Two isostructural H2O complexes were synthesized from different methods yet displayed different variable temperature magnetic...