Subotin V. Synthesis, structure and properties of coordination rhenium(IV,V) chalcohalides

The thesis deals with systematic study of complex formation in system: a rhenium compound – a liquid chalcogen-halides medium with an excess of chalcogen, for obtaining new homo- and heterochalcohalides of Re, determination of their composition, structure, physicochemical and catalytic properties. In the dissertation the scientific-practical problem of determination of catalytic activity of chalcogen-halide compounds of rhenium in the processes of hydrogenation of organic compounds is solved. Complex formation reactions were investigated in 44 systems, 10 chalcogenhalides of rhenium were synthesized, of which 4 were obtained for the first time, and others were synthesized by methods other than those described in the literature. The method of synthesis of a new tetranuclear cluster thioselenobromide of rhenium Re4S4Se4Br16 is developed. The structure of 10 chalcogen halides of rhenium has been established. It was found that in the synthesis medium with an excess of chalcogen at 100°C, mainly mononuclear chalcohalides of rhenium are formed, in some cases, the formation of triangular cluster rhenium chalcogenide skeletons [Re3Chal4] and [Re3Chal7] occurs. An increase in temperature to 200oC results in the formation of three- and four-core cluster chalcogen halides of rhenium with rhenium chalcogenide skeletons [Re3Chal7] and [Re4Chal4]. It was determined that with increasing temperature from 100оС to 200оС and selenium concentration there is a reducing of rhenium atoms with the transition of its electronic configuration from 5d0 to 5d3 state. In chloride systems, coordination chalcohalide compounds ReSCl3, ReSe4Cl6 and trinucleus clusters are formed. In bromide only cluster structures are formed - tri- and tetranuclear chalcohalides are formed. The quantum-chemical calculations of the electronic state of the ReSCl3, Re3Se3S4Br13 and Re4Se4S4Br16 complexes within the framework of the theory of density functional (DFT) have been carried out, which confirmed the proposed structures of the synthesized compounds and showed the metal (ReSCl3) and the semiconductor nature of Re4Se4S4Br16. It was found that the structure of the compounds is formed predominantly by a system of covalent bonds and weak Re-Re bonds. The IR and Raman spectroscopic characteristics of the rhenium chalcohalides obtained, in particular, the presence of bandwidth absorption bands of (Re-Hal), (Re-Chal), (Re-μ3-Chal), (µ-Chal22), (Re-Re). It has been shown that products of hydrolysis of synthesized rhenium chalcogen halides can be effective catalysts in reactions of liquid phase hydrogenation of quinoline, aromatic carboxylic acids and their esters. It was found that the maximum yields (~ 100%) of the products of catalysis were observed when using the hydrolysis product of Re3Se3S4Br13 as a catalyst in the range of temperatures of 50-150°C and a pressure of 1-50 atm. within 1-24 hours.