Synthesis, characterization, and properties of some copper(II) complexes of 2-pyridineformamide thiosemicarbazone (HAm4DH)

Reactions between different copper(ii) salts and 2-pyridine-formamide thiosemicarbazone (HAm4DH) in neutral ethanolic media led to the formation of complexes with the formulae [Cu(HAm4DH)X-2] (X = Cl or Br) (1, 2) and [Cu(HAm4DH)2]X-2 (X = NO3 or ClO4) (3, 4). The same reactions carried out in the presence of triethylamine gave rise to new complexes with the general formulae [Cu(Am4DH)X] (X = Cl, Br, AcO, or NO3) (5-8), [Cu(H2O)(Am4DH)1(ClO4) (9), and [Cu(Am4DH)(2)] (10), many of which were isolated with different molecules of crystallization and contain a deprotonated thiosemicarbazone (Am4DH). These complexes were characterized by elemental analysis, and different spectroscopic and magnetic techniques. The thermal and redox behavior of the complexes was also evaluated. Complexes 1, 2, 5, and 6 show better nuclease activity than [Cu(phen)(2)](2+). In addition, crystals were isolated in the cases of [Cu(HAm4DH)Cl(2)l(2) (5a), (1)(infinity)[Cu(Am4DH)Cl] (5b), (1)(infinity)[Cu(Am4DH)Br] (6a), and [Cu(HAm4DH)(H2O)(ClO4)(2)]center dot MeOH center dot H2O (9a) and these structures were analyzed by X-ray diffraction. Compound 5a has a dimeric structure with chlorine bridges and shows weak antiferromagnetism (J = -12.2 cm(-1)). Complexes 5b and 6a are one-dimensional polymers formed through halogen bridges and the deprotonated thiosemicarbazone in the thiolate form. In compound 9a the copper(ii) is in a distorted octahedral environment with two ClO4 units coordinated to the metal center. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)