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COMMON PART

Project Number22-13-00426

Project titleSynthesis, structure and biological activity of coordination compounds of 4, 5, 14 and 15 group elements with dioxygen ligands

Project LeadPrikhodchenko Petr

AffiliationKurnakov Institute of General and Inorganic Chemistry RAS,

Research area 03 - CHEMISTRY AND MATERIAL SCIENCES, 03-203 - Chemistry of coordination compounds

Keywordshydrogen peroxide, coordination chemistry, peroxocompounds, coordination compounds, peroxocomplexes, dioxygen ligands, inorganic chemistry, complexation, synthesis, p-block element, d-block element

PROJECT CONTENT

Annotation
Coordination compounds containing various forms of dioxygen ligands (molecular oxygen О2, superoxide anion (О2) -, hydroperoxide anion OOH-, peroxide anion (О2)2-) are involved in key biological processes of living organisms, including cellular respiration, signaling and protective functions and determine cell death. On the other hand, dioxygen complexes of transition metals are intermediate compounds in the selective catalytic oxidation of organic compounds. In addition, oxidation reactions involving molecular oxygen are often associated with the formation of dioxygen complexes at the corresponding coordination centers. Several directions in the coordination chemistry of dioxygen remains insufficiently studied despite the relevance of this field of coordination chemistry, which is confirmed by the annual growth in the number of scientific publications on this topic. For example, coordination compounds with hydroperoxoligands remains a relatively poorly studied class of dioxygen complexes: only 20 such compounds have been structurally characterized, which is only about 1% of the structural data on dioxygen complexes. At the same time, it is well known that protonated dioxygen ligands exhibit increased activity in catalytic processes. In addition, due to their nucleophilicity, coordinated hydroperoxo groups react with coordination centers with the formation of peroxo bridging structures, releasing a hydrogen peroxide molecule. Apparently, the high reactivity of hydroperoxo complexes complicates their preparation and study. Hydroperoxo complexes can be disproportionated to form superoxo derivatives, which can be stabilized by coordination with the p-block element. Complexes with organic peroxides remain another poorly studied class of coordination compounds. Most of them are currently represented by derivatives of commercially available tert-butyl and cumyl peroxides. However, the chemistry of organic peroxides has developed rapidly in recent years. The use of these compounds as ligands for the preparation of new peroxo complexes can solve the problems of their stabilization and maintains a number of useful properties, including high biological activity. Dioxygen coordination compounds with peroxo-bridging ligands binding the atoms of the transition and non-transition elements also remain unexplored. At the same time, such structures can have high reactivity while maintaining stability due to the coordination of the dioxygen with the p-block element. This project is supposed to solve an actual scientific problem associated with the synthesis and study of the physical, chemical properties and biological activity of new stable coordination dioxygen compounds. It is proposed to use 4, 5, 14 and 15 group elements of the periodic table as coordination centers, since these elements are stable in higher oxidation states and able to form stable dioxygen compounds with various types of coordination. These elements are convenient objects for the implementation of new synthetic approaches, which it is supposed to be used to solve scientific problems and tasks of this project. The use of organoelement coordination compounds containing one or more hydroxoligands coordinated with the element of groups 4, 5, 14 or 15 of the periodic table is suggested as one of such synthetic approaches, since such initial systems react with hydrogen peroxide or organic hydroperoxides without any additional conditions. The use of concentrated hydrogen peroxide and its solutions in anhydrous solvents is proposed as a new approach, which will make it possible to obtain and characterize previously unknown peroxocomplexes, for example, coordination compounds in which metal atom is coordinated with two hydroperoxo groups. The important task to be solved in this project is the search for new compounds with biological activity. For this, the synthesized complexes will be tested for anthelmintic, fungicidal, antiviral, antimalarial and antitumor activity. Thus, the solution of a scientific problem associated with the preparation and study of the physical and chemical properties of a new stable coordination dioxygen compounds with high biological activity implies a combination of approaches of inorganic, organic, physical and coordination chemistry, which are supposed to be used in the course of this project.

Expected results
The following results are expected to be obtained in the course of solving tasks within the framework of the designated scientific problem. The synthesis of organoelement compounds of elements 4, 5, 14 and 15 groups of periodic table containing hydroxo- or halide ligands will be carried out for use as precursors in the preparation of coordination compounds with dioxygen ligands. Anhydrous hydrogen peroxide and its solutions in organic solvents will be obtained from serine peroxohydrate for the synthesis of hydroperoxo and peroxo complexes. Alkali metal salts for available and synthesized organic hydroperoxides will be obtained for subsequent use in the synthesis of coordination compounds. In the salts the proton of the hydroperoxo group is replaced by an alkali metal cation. The conditions for the coordination dioxygen compound formation will be investigated in the reaction system by the NMR and optical spectroscopies. Thus, spectral data will be obtained indicating the coordination of the dioxygen ligand with the coordination centre. The coordination compounds of p-block elements with hydroperoxide anions as ligands will be isolated in solid form, including as single crystals suitable for investigation by X-ray structural analysis. The crystal structure will be determined for a number of new hydroperoxo complexes. The possibility of obtaining peroxo complexes in which coordination centre is coordinated with three hydroperoxo groups will be investigated. The possibility of disproportionation of the initial hydroperoxo and peroxo derivatives will be investigated with the formation of superoxide complexes under the heating or UV irradiation. It is proposed to involve EPR, optical spectroscopy, and X-ray diffraction in order to determine the conditions for obtaining systems with the maximum concentration of superoxide radical. The possibility of the formation and isolation of dioxygen coordination compounds with peroxo bridging ligands binding the atoms of the transition and non-transition elements using hydroperoxides of alkyl and aryl derivatives of p-block elements as starting compounds will be investigated. Coordination compounds 4, 5, 14 and 15 group elements of the periodic table with organic peroxides as ligands will be obtained. The synthesis will be carried out using the salts of alkali metals of available and synthesized organic hydroperoxides. The effect of the nature of the coordination centre, the number and nature of ligands on the type of coordination of the organic peroxide and the properties of the complex, including the stability of the obtained compounds will be investigated. The possibility of coordination organic peroxides R-O-O-R' with 4 and 5 element groups will be investigated, the composition, structure and properties of such coordination compounds will be established. Preparation of coordination compounds with various elements will solve the problem of stabilizing organic peroxides. Systems containing starting and target products will be characterized by a set of physical and chemical methods of analysis NMR spectroscopy (1Н, 13С, 17О, 27Al, 29Si, 77Se, 119Sn, 207Pb, etc.), IR-, Raman- and UV-vis spectroscopy, differential scanning calorimetry and thermogravimetry, EPR spectroscopy, powder X-ray diffraction, high-resolution scanning electron microscopy, single crystal X-ray diffraction analysis and other methods. Biological activity studies of the obtained coordination compounds with dioxygen ligands will be carried out. For this, the synthesized complexes will be tested for anthelmintic, fungicidal, antiviral, antimalarial and antitumor activity. Conclusions about the prospects of using the obtained dioxygen coordination compounds as biologically active compounds will be made. The correspondence of the proposed results to the world level is justified by the relevance of the scientific problem associated with the preparation and study of the physical and chemical properties of new stable coordination dioxygen compounds with high biological activity. The obtained data will be of high scientific significance not only from the point of view of the fundamental chemistry of coordination dioxygen compounds, but also the possibility of practical use of the expected results, since promising compounds with high biological activity will be proposed.

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