Copper(II) pyridine-2,6-dicarboxylates. Coordination and distortion isomers of [Cu(pydca)(H2O)(2)]

Copper(II) pyridine-2,6-dicarboxylate dihydrate and its ronicol (ron), nico tinamide (nia) and caffeine (caf) complexes were prepared and their spectra l, magnetic as well as their bio-activites were studied. X-ray analysis of [Cu(pydca)(H2O)(2)] (pydca = pyridine-2,6-dicarboxylate) shows, that the co mplex exists in two isomeric forms: monoclinic and triclinic and it is an e xample of the coordination isomerism. Triclinic forms also exists in two is omeric forms, differing mostly by degree of distortion and being an example of the distortion isomerism. On the basis of spectral and magnetic propert ies for Cu(pydca)L (L = ron, nia or caf) a square-pyramidal coordination of the copper(II) ion can be proposed. Highest bio-activity shows [Cu(pydca)( H2O)(2)].