NICKEL(II) AND COPPER(II) COMPLEXES WITH AMIDRAZONE-BASED LIGANDS - STRUCTURE AND CATALYTIC ACTIVITY

Nickel(II) and copper(II) complexes MeL, where H(2)L = [9-(2'-hydroxyphenyl)-6-methyl-3-acetyl-5,7,8-triazanona-3,6,8-trien-2-one] have been synthesized by template reaction of salicylaldehyde acetamidrazone with corresponding Me(acac)(2) and Hacac in the presence of the orthoformic ester at 110 degrees C. The crystal structure of CuL has been determined by X-ray diffraction. The square-planar mode of coordination is realized in CuL. Comparison of geometrical parameters of CuL with those of the corresponding derivative based on S-allylisothiosemicarbazide showed that substitution of the - SR group by methyl in the quadridentate ligand does not affect the mode of binding nor the main interatomic distances and angles in the ligand. The data from magnetic measurements, H-1 NMR and EI mass spectra indicate that NiL has a similarly structured coordination polyhedron. Epoxidation of norbornene can be performed efficiently with molecular oxygen (1 atm) in THF (or THF-EtOAc) in the presence of Cut at 70 degrees C. The corresponding copper(II) derivatives based on S-substituted isothiosemicarbazides are much less active as catalysts.