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This study provides a comparative characterization of the structural parameters and cytotoxicity of zinc halide and copper(II) bromide complexes with caffeine (caf) of the composition [Zn(caf)(H2O)X2] (X = Cl, Br, I) and [Cu(caf)2Br2] (1). The cytotoxicity of the complexes is dose-dependent in all cell lines. The concentrations of the complexes, at which they are more cytotoxic against cancer cells (MCF-7) than against stem cells (DPSC), were determined. The synthesized complexes exhibited synergism of cytotoxicity.

Nickel(II) complexes of the composition [NiLn][B10H10] (L = DMF, H2O, n = 6; L = N2H4, n = 3) have been synthesized and studied. The thermal reduction of the complexes has been studied in the temperature range 20–800°C in air and in an inert atmosphere. Precursor complexes and their reduction products have been identified by elemental analysis, X-ray powder diffraction, and IR spectroscopy. The physicochemical study of the thermolysis product of complex [Ni(DMF)6][B10H10] shows that scarcely studied solid solutions of the composition Ni3C1 –xВx are formed.

Solid solutions based on MgMnO3 – δ in which magnesium is partially substituted for by lithium were produced by solid-phase synthesis by air annealing of mechanocomposites obtained by mechanical activation (in a vibration ball mill) of mixtures of high-purity grade precursors: oxides MgO, Mn2O3, and MnO2, and also Li2CO3 and LiOH · H2O. It was shown that using lithium hydroxide monohydrate increases the degree of substitution of lithium for magnesium with simultaneous decrease in the synthesis temperature in comparison with using lithium carbonate.

Complexes [CoLn][B10H10], where L = H2O, n = 6; L = N2H4, n = 3, have been synthesized and characterized. The possibility of their use as precursors for the synthesis of binary cobalt(II) borides has been shown. Cobalt(II) borides have been obtained by thermal reduction of precursor complexes in an inert atmosphere at 650 and 900°C. The purity and homogeneity of the precursors and their reduction products have been determined by elemental analysis, powder X-ray diffraction, and IR spectroscopy; magnetochemistry of precursors and their annealing products has been studied. The morphology of the final products has been studied. It has been found that the reduction products are structured oxide-boride and nitride-boride phases. The magnetochemical study of the phases showed a significant difference in their magnetic behavior.

Lithium-rich superstoichiometric solid solutions MgLixMnO3 – δ were obtained by intercalation into the spinel MgMnO3 – δ using lithium hydride LiH as an intercalating agent through the stage of the formation of mechanocomposites. The accompanying chemical transformations involving the hydride ion were studied. Conventional ceramic synthesis methods and alternative intercalating agents were analyzed. It was shown that hydride intercalation produces pure samples of single-phase spinels with high lithium content (MgLi0.75MnO3), which is three times higher than that reachable by conventional ceramic synthesis methods.

The formation of complex salt [Ag(PPh3)4][2-B10H9NH3 ∙ 2DMF] (I) by the reaction of the salts of the [2-B10H9NH3]– anion with [Ag(PPh3)4]NO3 is studied. The anionic moiety of complex I is a stable solvate linked by hydrogen bonds of two types. Compound I is identified by IR spectroscopy and elemental, X-ray structure, and X-ray diffraction analyses (CIF file CCDC no. 1884451).

Complexes [Co(solv)n][B10H10], where (I: solv = H2O, n = 6; II: solv = N2H4, n = 3) have been synthesized and characterized. The possibility to use them as precursors in the synthesis of binary borides has been demonstrated. The purity and homogeneity of the precursors and the products of their thermal reduction (in an inert atmosphere at 650 and 900°С) has been established by elemental analysis, X-ray powder diffraction, and IR spectroscopy; magnetochemical studies of the precursors and their annealing products have been carried out. According to the data obtained, the reduction products are structured oxide-boride and nitride-boride phases, respectively. Magnetochemical study of the phases has revealed a significant difference in their magnetic behavior: the oxide-boride phase is characterized by a significant ferromagnetic contribution to the total magnetization of the sample, while the nitride-boride phase, by a diamagnetic contribution.

Molecular complexes [Zn(caf)(H2O)I2] (I), [Zn(caf)(H2O)Cl2] (IV), and the polymeric ones {[Cd(H2O)2I2](caf).2H2O}n (II) and {[Cd(H2O)2Br2](caf).2H2O}n (III) consisting of infinite Cd-containing chains with bridging halide ions and water molecules in trans-position and connected with each other due to hydrogen bonding with participation of caffeine (caf) and water molecules, were prepared and characterized by the powder and single crystal X-ray diffraction, IR vibrational spectroscopy, 1H NMR, ESI-MS spectroscopy, thermal analysis and DFT calculations. It was found that the complexes (I) and (IV) are characterized by tetrahedral geometry, the caffeine molecule being coordinated by the central atom via its N9 atom. The preferability of complex formation was evaluated by quantum-chemical calculations. Cyto- and genotoxicity of the compounds have been investigated and discussed in comparison with that of [Zn(AP)2I2] (1) and [Cd(AP)6][Cd(AP)I3]2 (2). It was demonstrated that the prepared complexes, primarily that of cadmium iodide with caffeine (II), are the promising ones for further studies both in vitro and in vivo.

The method of synthesis of nanoscaled sodium dodecahydro-closo-dodecaborate Na2[B12H12] is presented. The desired product has been prepared by heating to 200°C the composite formed by the introduction of the triethylammonium salt [Et3NH]2[B12H12] into the silicate matrix of sodium liquid glass. The morphology and phase composition of the synthesized sample have been studied by SEM and X-ray diffraction methods in comparison with regular Na2[B12H12] salt. According to the obtained data, the sample under study is an amorphous composite, on the surface of which nanoscale crystals of Na2[B12H12] are formed.

The thermal behavior of MgH2 mechanocomposites with Mg2NiH4 – δ + Mg2NiH0.3 two-phase mixture and phase equilibria in the system Mg–Ni–H involving MgH2 were studied by powder X-ray diffraction and TG–DSC. The graphic representation of phase equilibria involving MgH2 and Mg2NiH4 – δ and Mg2NiHx (0 < x < 0.3) solid solutions in the practically important field with high magnesium content area was revised. The possibility of MgH2 mechanocomposites with Mg2NiH4 – δ and Mg2NiHx for use as magnesium intercalating agents and alternative intercalating agents—organomagnesium compounds were considered.

The reactivity of the decahydro-closo-decaborate anion in the complexation of metals being among intermediates acids in the concept of the Pearson’s theory of hard and soft acids and bases is studied systematically in the presence of competitive ligands L. In continuing these studies, we have synthesized Zn(II) and Cd(II) complexes of the composition [М(DMF)6][B10H10] (M = Zn(II), Cd(II)) and studied them by physicochemical analyses (IR and UV spectroscopy, X-ray powder diffraction). The possibility of their use in solid-phase synthesis of the corresponding trischelate complexes [M(Bipy)3][B10H10] has been found. Complexes [М(DMF)6][B10H10] are formed by the reaction between triethylammonium closo-decaborate with metal nitrates in DMF. The compounds are isostructural with the corresponding Co(II) and Ni(II) complexes [М(DMF)6][B10H10]. Specific interactions have been found between the BH groups of the boron clusters and CH groups of the DMF molecules. According to the data of IR and UV spectroscopy, the complexes contain specific B–H···C–H interactions. The corresponding tris-chelate complexes of the metals [M(Bipy)3][B10H10] are also isostructural.

Copper(II) complexation reactions with neutral N-donor ligands (Bipy, Phen, NH3) in the presence of the bulky decachloro-closo-decaborate dianion were studied. Copper(II) complexes can be prepared from copper(II) salts or copper(I) salts by redox reactions proceeding in air. The complexes [Cu(Bipy)3][B10Cl10]·2CH3CN (1·2CH3CN), [Cu(Bipy)3][B10Cl10]·2Bipy (1·2Bipy), [Cu(Bipy)2Cl]2[B10Cl10]·2DMF (2·2DMF), [Cu(Phen)2Cl]2[B10Cl10]·DMSO·1.25H2O (3·DMSO·1.25H2O) and [Cu(NH3)4(CH3CN)2][B10Cl10] (4) were prepared and characterized by X-ray diffraction as well as IR and 11B NMR spectroscopies. Complexes 1·2CH3CN, 2·2DMF, and 4 were also studied using 35Cl NQR spectroscopy. Secondary interactions were selected from all the interatomic contacts found in these crystals by X-ray diffraction. Hydrogen N–H⋯Cl–B, C–H⋯Cl–B and p⋯π (B–Cl⋯C) secondary bonds were identified in all the compounds, the spectroscopic data being generally in accordance with the results of the X-ray diffraction.

Phase equilibria involving LiMn2O4-, Li2MnO3-, LiMnO2-, Mn3O4-, and MnO-base solid solutions were studied with varied temperature and partial oxygen pressure. The $${P_{{o_2}}}$$ –T and x–y projections of the P–T–x–y phase diagram of the Li–Mn−O system were constructed, as well as the key x–y isotherms of the Li2O–MnO–MnO2 quasi-ternary system. In some experiments, the authors’ hydride lithiation method was employed to prepare lithium-rich homogeneous three-component nonstoichiometric phases.

This survey analyzes the results of studies into Li(Na,K,Rb,Cs)/W/Mn/SiO2 composites, which are used as catalysts for oxidative coupling of methane (OCM). The focus is on phase states. Our analysis shows that the SiO2 matrix is an active constituent of the composites and not an inert carrier of additives and the OCM heterogeneous process involves alkali-metal tungstate melts, along with polycrystalline manganese oxides. The effects of the cation ratio and synthetic routes on the phase composition of Li(Na,K,Rb,Cs)/W/Mn/SiO2 are assessed.

Undoped lithiation of stoichiometric spinel using lithium hydride LiH up to the composition Li2.25Mn2O4 was performed. A homogeneous material with a given Li: Mn ratio was obtained by mechanochemical activation with sequential annealing of a LiMn2O4–LiH mixture in a high-purity argon atmosphere and then in air or oxygen at 373–553 K.

The synthesis and structure of complexes [Co(solv)6][B10H10] (solv = DMF and DMSO) have been reported. Both complexes have been prepared in a high yield by the reaction between cobalt(II) salts and closo-decaborates Cat2[B10H10] in the corresponding solvent. The complexes have been characterized by elemental analysis, IR and UV spectroscopy, X-ray powder diffraction, and X-ray crystallography. The thermal properties of the compounds have been studied in the temperature range 20–600°C under argon. The conditions to form cobalt borides have been determined based on the results of thermal analysis, subsequent annealing of the complexes in various conditions, and analysis of IR spectra of the resulting thermolysis products.