The thesis concerns the synthesis 3d-metal di- and trinuclear complexes with pyrazole-based symmetric and asymmetric ligands, their characterization and study of their catalytic properties, inhibition and magnetic behavior. A series of dizinc(II) dicopper(II), dinickel(II) and dimanganese(III) complexes based on pyrazolate ligands 3-[N-hydroxyethanimidoyl]-4-methyl-1H-pyrazole-5-carboxylic acid (PzOxCA), (4-Methyl-1H-pyrazole-3,5-diyl)diethanone dihydrazone (PzDHn), (4-methyl-1H-pyrazole-3,5-diyl)bis(methylmethanone) dioxime (PzDOx), (4-phenyl-1H-pyrazole-3,5-diyl)bis(phenylmethanone) dioxime (PhPzDOx) and 1H-pyrazole-3,5-dicarboxylic acid (PzDCA) has been synthesized and examined as functional models of phosphoesterases, focusing on correlations between hydrolytic activity and molecular parameters of the bimetallic core. Speciation of the various dizinc, dicopper, dinickel and dimanganese complexes in solution has been performed potentiometrically and spectrophotometrically, and the structures of 10 complexes in the solid state have been determined by X-ray crystallography. The hydrolysis of two phosphoesters, the 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) (as an RNA model) and the pesticide paraoxon-ethyl (POE) promoted by the dinuclear phosphoesterase model complexes has been studied in DMSO/buffered water (1:1) at 50 C as a function of complex concentration, substrate concentration and pH. Significant differences in hydrolytic activity of [Zn2(PzOxCA-2Н)2]0, [Zn2(PzDHn-Н)2]2+, [Zn2(PzDOx-H)2]2+, [Zn2(PzDCA-3Н)2]2- are observed and can be attributed to molecular peculiarities. The metal array and the complex framework seem to provide a sufficient number of coordination sites for both activating the substrate and generation of the nucleophile, where the phosphate esters are preferentially bound in a bidentate bridging fashion (in case of HPNP) and in a monodentate fashion (in case of POE). Three complexes [Cu2(PzOxCA-2Н)2(DМSО)(Н2О)]·Н2О, [Cu2(PzOxCA-2Н)2 (DМSО)2]·Н2О and [Cu3(PzOxCA-3Н)2(Py)5] havebeen isolated. The former feature a bis(pyrazolato)-bridged dicopper core, whereas in the latter adjacent copper ions are spanned by a pyrazolate and an oximate. The presence of different species in solution depending on the pH has been demonstrated by EPR. Alterations in the protonation state are accompanied with changes in nuclearity, which cause pronounced changes in color, magnetic and EPR properties. Magnetic susceptibility measurements in the temperature range 1,7-300 K have revealed antiferromagnetic exchange coupling between copper(II), nickel(II) and manganese(III) ions in all complexes.
