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Role of Ni(Fe)-macrostructures due to H-bonds in mechanisms of Ni(Fe)ARD action in methionine salvage pathway is discussed. The AFM method was used to research the possibility of the formation of stable supramolecular nanostructures based on Ni(Fe)ARD model systems {Ni(acac) 2 + L 2 + Tyr} (L 2 = NMP (NMP = N-Methyl-2-pirrolidone), His (His = L-Histidine), Tyr (Tyr = L-Tyrosine)-with the assistance of intermolecular H-bonds. In the course of scanning of investigated samples, it has been found that the structures based on model systems are fixed on a surface strongly enough due to H-bonding. The self-assembly-driven growth of the supramolecular structures on modified Silicone surface based on researched complexes, due to H-bonds and perhaps the other non-covalent interactions was observed.

The possibility of the supramolecular nano structures formation on the basis of iron and nickel heteroligand complexes: Fe x (acac) y 18C6 m (H 2 O) n , and Fe x (acac) y (CTAB) p (H 2 O) q , or Ni 2 (OAc) 3 (acac)L 2 ·2H 2 O (L 2 = MP) − with the assistance of H-bonding, is researched using the AFM method. Formation of different supramolecular nanostructures on the basis of nickel and iron heteroligand complexes as models for Ni(Fe)ARD Dioxygenases may be used for understanding of different actions of these enzymes.

The oxidation of alkylarenes by dioxygen in the presence of complexes of nickel and cobalt with macrocyclic ethers 18-crown-6 and 15-crown-5 was studied. The conditions for selective catalytic oxidation of ethylbenzene to ct-phenylethyl hydroperoxide were determined. The kinetics of the accumulation of all oxidation products was studied. The order o( the fom~ation of the products at different stages of chain oxidation was determined. The activity of the complexes at the elementary stages of the chain oxidation of ethytbenzene is discussed.Key words: oxidation, dioxygen, homogeneous catalysis, macrocyclic polyethers, nickel and cobalt complexes, ethylbenzene.The efficiency of oxidation of alkylarenes by dioxygen to the corresponding hydroperoxides in the presence of metal bisacetylacetonates can be substantially increased by using two-component catalytic systems M(acac)2--L (M = Ni n, Coil; L is N-methylpyrrolidone-2, HMPA, DMF, or another electron-donating ligand capable of coordinating to the fifth coordination site of the metal).t-4We have previously established 3 that the mechanism of controlling the catalytic activity of M(acac) 2 by monodentate ligands changes in the course of oxidation. At the initial stages, the activation of dioxygen by the M(acac) 2 9 L complexes and the homolytic decomposition of ROOH under the action of the complexes play the most important role. Later in the process, the selectivity of oxidation increases due to transformation of the complex promoted by the L ligand. This increase in selectivity is achieved by the participation of the transformed form of the complex in chain initiation and by a considerable decrease in the rates of both homolytic and heterolytic decomposition of the hydroperoxides. The mechanism of transformation of the catalyst in the course of oxidation depends on the nature of the metal.[n the case of Ni(acac)2, this transformation involves dioxygen. The limiting stage of the process is the regioselective addition of O, to the u atom of the acac-ligand. This addition is controlled by the L ligand and results in the oxidation of the acetylacetonate ion to the acetate iota. It is assumed that for the Co(acac)2--L system the central metal ion rather than the acaciigand is oxidized and, most likely, free peroxide radicals RO 2' act as tile oxidant. 4When the monodentate L ligand is replaced by macrocyclic polyether 18-crown-6 (18C6), the initial oxidation rate (w ~ and selectivity (S) increase substantially due to the fact that the activity of the "primary" M(acac)2-18C6 complexes in chain initiation is higher than that of M(acac) 2 activated by monodentate ligands and their activity in reactions of branching and propagation of the oxidation chain is lower, sAs in the presence of monodentate ligands, in the course of oxidation, the M(acac) 2 9 18C6 adduct is transformed into a more catalytically active form, and the selectivity of the oxidation increases.In the present work, the oxidation of ethylbenzene in the presence of Ni 11 and CO Il complexes with macrocyclic pol...

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