Extended structures in copper(II) complexes with 4-hydroxypyridine-2,6-dicarboxylate and pyrimidine derivative ligands: X-ray crystal structure, solution and magnetic studies

Three new copper(II) complexes of chelidamic acid (H(3)cda) and pyrimidine derivatives, namely [Cu-2 (Hcda)(2)(ampym)(2)]center dot 5H(2)O (1) and [Cu-2(Hcda)(2)(apym)(H2O)(2)]center dot 2H(2)O (2), and (Hapym)(2)[Cu(Hcda)(2)]center dot 4H(2)O (3) (ampym = 2-amino-4-methylpyrimidine, apym = 2-aminopyrimidine) have been synthesised in mild conditions starting from the proton transfer compounds (Hampym)(2)(Hcda) and (Hapym)(2)(Hcda). X-ray diffraction analysis revealed the formation of extended structures featuring dinuclear (1 and 2 with pyrimidine derivatives as metal bridges) or mononuclear (3) Hcda(2) copper(II) complex units joined via H-bonds mainly involving coordinated and lattice water molecules and the coordinated Hcda(2) ligands. Solution studies, magnetic measurements and thermal analyses were performed to fully characterise the new compounds.