Dicopper(II) Complexes of the Antitumor Analogues Acylbis(salicylaldehyde hydrazones) and Crystal Structures of Monomeric [Cu2(1,3-propanedioyl bis(salicylaldehyde hydrazone))(H2O)2]·(ClO4) 2·3H2O and Polymeric {Cu2(1,6-hexanedioyl bis(salicylaldehyde hydrazone))

Abstract

Salicylaldehyde hydrazones derived from acyldicarboxylic acids (H4Ln, where n = 0, 1, 2, 4, 6, 8, 10, 14 and is the number of methylene units) of varying chain length have been prepared, and their dicopper(II) complexes have been isolated as bis analogues of antitumor carboxylate hydrazones. The predominant structural form adopted is polymeric, with [{Cu2Ln}m] formed in neutral or basic solution, [{Cu2(H2Ln)Cl2}m] from dilute HCl, and [{Cu2-(H2Ln)}ml·(ClO 4)2m, from dilute HClO4. The crystal structures of [Cu2(H2L1)(H2O) 2]·(ClO4)2·3H2O and [{Cu2(H2L4)(C2H5OH) 2}m]·(ClO4) 2m]·m(C2H5OH) have been determined. The structure of [Cu2(H2L1)(H2O)2]· (ClO4)2·3H2O consists of discrete di-Cu(II) molecules with nonsymmetry-related Cu(II) centers. The copper atoms are square-planar with H2L1 supplying two tridentate, monoanionic ONO domains and water completing the coordination sphere. The two metal-binding domains are inclined at 80° to each other. For [{Cu2(H2L4)(C2H5-OH) 2}m]·(ClO4) 2m·m(CVH5OH) the symmetry-related copper atoms are square-pyramidal with the base composed of H2L4. acting as a tridentate ONO chelator, and an O-bonded ethanol molecule. Axial phenolato bridges complete the coordination sphere, linking molecules to give a polymer. Compounds prepared have been characterized by a range of physicochemical and spectroscopic techniques, and proton and metal ion stability constant data have been determined.