Two rhenium complexes with reduced forms of iminoquinone as ligands (LDipp = N-(2,6-diisopropylphenyl)-3,5-di-tert-butyl-o-benzoquinoneimine), [ReCl3(LDipp)(PPh3)] (1) and [ReCl3(LDipp)(OPPh3)] (2), have been synthesized. The metrical oxidation states (MOS) of the iminoxolene ligand LDipp in both complexes, equal to -1.29(9), -1.36(11) and -1.44(8) for structures 1, 2 and 2·4C6H6, respectively, lie between the values for iminosemiquinolate ((ISQDipp)-·) and amidophenolate ((APDipp)2-). The 1H and 13C NMR spectra of both complexes exhibit paramagnetically shifted but narrow signals, allowing the use of conventional 2D NMR techniques for the complete assignment of H and C atoms. High-level ab initio calculations revealed a pronounced multi-configurational nature of the ground triplet state of both complexes, with the spin population localized predominantly on Re, with some delocalization of the negative spin density to iminoxolene. Magnetic measurements showed that, for both complexes in the range of 2-300 K, the χT product increases almost linearly with temperature, in quantitative agreement with the results of high-level ab initio calculations, which predicted very high positive values of the ZFS parameter D for the ground triplet states of both complexes.

Due to a unique set of properties, octahedral cluster complexes of molybdenum and tungsten [{M6I8}L6]n are promising for various applications. However, the majority of studies focus on homoleptic compounds, while heteroleptic analogues remain largely unexplored. This work examines the interaction of iodide cluster complexes (Bu4N)2[{M6I8}I6] (M = Mo, W) with dimethyl sulfoxide, resulting in the synthesis and structural characterization of four new heteroleptic complexes (Bu4N)[{M6I8}(DMSO)I5] and cis-[{M6I8}(DMSO)2I4] (M = Mo, W). Using 1H NMR spectra to monitor reaction mixtures and varying the synthetic conditions (including I2 addition), we tracked the formation of deeper substitution products, up to the homoleptic [{M6I8}(DMSO)6](I3)4 (M = Mo, W), previously reported by us. This study allowed us to identify the most stable products under synthesis conditions and elucidate the isomeric pathway of the substitution process. The optical and luminescent properties of the new heteroleptic complexes were studied. Partial substitution of terminal ligands was shown to significantly reduce the photophysical characteristics.

Aza[5]helicenes of the furoquinoline series have two important features: (a) possibility to modulate photophysical properties by protonation, and (b) they are good fluorophores that exhibit exceptional photostability in chlorine-free organic solvents. Light irradiation in chlorine-containing solvents was known to result in photoprotonation. In this work photophysics and photochemistry of a typical aza[5]helicene, namely 3-methoxy-6-(4methoxyphenyl)naphtho[1 ',2 ':4,5]furo[2,3-c]quinoline (compound Hel) in dichloromethane (DCM) was studied using stationary photolysis with UV-Vis and NMR registration, time-resolved fluorescence and nanosecond laser flash photolysis. The free base aza[5]helicene was found for the first time to promote the transformation of dichloromethane to chloroform upon irradiation with UV light (308 nm). Studies of the quantitative characteristics of Hel and HelH & thorn; (fluorescence quantum yields, spectra and kinetic properties of the triplet states -showed that photoprotonation occurs in two ways. The first pathway is started by an electron transfer from an excited Hel molecule to a solvent molecule, followed by an H atom transfer from a solvent molecule to the Hel center dot & thorn; radical cation. The second pathway of HelH & thorn; formation is the reaction between Hel and HCl formed at the first stage. A quantitative mechanism of photoprotonation is proposed that explains all the observed experimental data.

Reaction of [Zr(η5-Cp’)2Cl2] (Cp’ = tBuC5H4) and Na2Cat36 (Cat36 = 3,6-di-tert-butylcatecholate) leads to the formation of the complexes [Na2Zr(Cat36)3(THF)2(C7H8)] (1) and [Zr(η5-Cp’)2(η1-Cp’)2] (2). Complex 1 along with its congeners [K2Zr(Cat36)3(THF)2] (3), [Li(THF)4][LiZr(Cat36)3] (4) and [Li4Zr(Cat36)4(dme)2] (5) were synthesized by the reaction of [ZrCl4(THF)2] and corresponding alkali metal catecholate M2Cat36. The complexes obtained were characterized by means of single-crystal X-ray diffraction and solution NMR spectroscopy (1H, 7Li, 13C). Relatively short Li···H contacts are present in the structures of complexes 4 and 5; nevertheless, DFT calculations have shown no covalent contribution to these interactions.

Despite the high practical potential of octahedral iodide molybdenum cluster complexes [M6I8L6]n, their further development is still hindered due to their hydrolytic instability. Some success in stabilizing the complexes in aqueous solutions has been achieved by using certain ligands, but so far, the type of ligand still has an unpredictable influence on the stability of these compounds. Therefore, obtaining new water-soluble clusters and studying their behavior in aqueous medium is an urgent task. In this work, a new representative of cluster compounds - Na2[Mo6I8(GA)6] (where GA- is an anion of glycolic acid) - has been synthesized and characterized in detail. The study of its hydrolytic stability showed the formation of an insoluble mixed-ligand neutral complex - trans-[Mo6I8(H2O)2(GA)4], which is a first example of the cluster of such type bearing carboxylate ligands. Photoluminescence was studied for the obtained compounds.

The metathesis of ammonium cations in (NH4)4[Mo12O28(μ-L)8] (L = pz (pyrazolate) and trz (1,2,4-triazolate)) with tetrabutylammonium is performed under boiling in an aqueous solution with Bu4NOH. The substitution of cations and the preservation of the anionic cluster fragment are confirmed by a number of physicochemical methods such as XRD, 1H NMR, and mass spectrometry. The resulting compounds are soluble and stable in organic solvents, so their redox properties are studied. According to the cyclic voltammetry data, the compounds exhibit reversible oxidation with E1/2 = 0.26 V and 0.61 V for L = pz and trz respectively. The electronic structure is studied by quantum chemical calculations. It is shown that the frontier molecular orbitals of these compounds are mainly composed of molybdenum d-orbitals.

Developing the chemistry of octahedral chalcogenide molybdenum and tungsten cluster complexes in the context of applications in biology and medicine, in this work a series of water-soluble neutral cluster complexes [{M6Q8}(P(C2H4CONH2)3)6] (M = Mo, W; Q = S, Se) have been obtained by simultaneous replacement of inner and terminal halide ligands in [{M6I8}I6]2- with chalcogenide and organic phosphine ligands and characterized by single-crystal X-ray diffraction analysis, 1H and 31P NMR spectroscopies, elemental analysis, and UV-vis spectroscopy. The amide groups of the organic ligands, on the one hand, contribute to the solubility of the resulting clusters in water and, on the other hand, are able to form an extensive network of hydrogen bonds, leading to the crystallization of the complexes from aqueous solutions. Despite this fact, the complexes have sufficient solubility and stability in aqueous solutions, which made it possible to demonstrate their low cytotoxicity on Hep-2 cells (IC50 were not reached even at concentration up to 4 mM). The resulting clusters are among the most biocompatible of the octahedral clusters studied to date and are the starting point for the development of a new family of X-ray contrast agents.

In this work, we present six new zinc(II) complexes with the general formulas [Zn2(oligopyridine)2L4] and [Zn (oligopyridine)2L2], where L- = 5-(4-chlorophenyl)-1H-tetrazolate anion, and oligopyridine = 1,10-phenanthroline or 2,2 '-bipyridine derivatives (dmphen - 4,7-dimethyl-1,10-phenanthroline, phen - 1,10 phenanthroline, dmbipy - 2,2 '-bi-4-picoline, bipy - 2,2 '-bipyridine), which have been synthesized with high yield and characterized by IR spectroscopy, elemental, thermogravimetric, single crystal and powder X-ray analyses. A distorted square-pyramidal and octahedral geometry of zinc(II) ion have been demonstrated by single crystal Xray diffraction analysis. The tetrazolate ligand exhibits two types of coordination: monodentate, and bidentatebridging via the N(2), N(3) or N(1), N(2) atoms. The behavior of all complexes in solution has been investigated by UV-Vis and the 1H, 13C NMR spectroscopy, conductometry, and mass spectrometry. The antimicrobial study of the compounds has been carried out against E. coli, St. aureus, P. italicum, and C. steinii, and [Zn2(dmbipy)2L4] has been shown to possess significant protistocidal properties. According to the cytotoxicity study,all complexes don't have cytotoxic properties in 1-100 mu M concentration range against tumor human cell lines (larynx carcinoma Hep2, hepatocellular carcinoma HepG2 and breast adenocarcinoma MCF-7) with the exception of complex 5 which has displayed significant cytotoxic effect (LC50 = 19.8 +/- 2.4 mu M) against Hep2 cells. However, obtained compounds have a pronounced cytostatic effect on all tumor cell lines.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The chemistry of transition metal clusters has been intensively developed in the last decades, leading to the preparation of a number of compounds with promising and practically useful properties. In this context, the present work demonstrates the preparation and study of the reactivity, i.e., the possibility of varying the ligand environment, of new square pyramidal molybdenum chalcogenide clusters [{Mo5(μ3-S)i4(μ4-S)i(μ-pz)i4}(pzH)t5]1+/2+ (pzH = pyrazole, i = inner, t = terminal). The one-step synthesis starting from the octahedral Mo6Br12 cluster as well as the substitution of the apical pyrazole ligand or the selective bromination of the inner pyrazolate ligands were demonstrated. All the obtained compounds were characterized in detail using a series of physicochemical methods both in solid state (X-ray diffraction analysis, etc.) and in solution (nuclear magnetic resonance spectroscopy, mass spectrometry, etc.). In this work, redox properties and absorption in the ultraviolet-visible and near-infrared region of the obtained compounds were studied.

1H-tetrazole-5-acetic acid is bifunctional ligand that was employed for the synthesis of zinc(II) complexes in the presence of secondary ligands such as oligopyridines (dmphen - 4,7-dimethyl-1,10-phenanthroline, phendione - 1,10-phenanthroline-5,6-dione, phen - 1,10-phenanthroline, dmbipy - 2,2'-bi-4-picoline, bipy - 2,2'-bipyridine). Five new mixed-ligand zinc(II) complexes [Zn(dmphen)L]center dot H2O (1), [Zn(phendione)(H2O)L]center dot 2H(2)O (2), [Zn(phen) L]center dot 0,5H(2)O (3), {[Zn(dmbipy)L]center dot H2O}(n) (4) and [Zn(bipy)L]center dot H2O (5) have been synthesized and characterized by elemental analysis, IR spectroscopy and powder X-ray diffraction. All complexes have shown to possess thermal stability up to 250 degrees C by thermogravimetric analysis, except for complexes 2 and 5, which have been stable up to 200 degrees C. Crystal structures of polymeric complexes {[Zn(dmphen)(H2O)(2)L]center dot 2H(2)O}(n) (1a) and 4 have been determined by single-crystal X-ray diffraction analysis. The effect of the compounds on viability of HepG-2, MCF-7 and MRC-5 cell lines has been investigated. Complex 2 was found to be the most cytotoxic with IC50 values of 6.4 +/- 0.9 mu M for HepG-2 cells and 2.6 +/- 1.1 mu M for MCF-7 cells. The antimicrobial activity of the complexes and ligands has been investigated against E. coli, S. aureus, P. italicum and C. steinii.

Octahedral cluster complexes of molybdenum and tungsten, [M6X8Y6]n- (M = Mo, W; X, Y = Cl, Br, I), are promising active components in various fields, including biomedicine and solar energy. Cluster complexes draw considerable attention due to their X-ray opacity, red/near-IR luminescence, and ability to convert triplet molecular oxygen to active singlet oxygen under UV and visible irradiation. Among the octahedral cluster complexes of molybdenum and tungsten, compounds with a {W6Br8}4+ core are the least studied. There are only a few examples of compounds with substituted terminal ligands, and their properties are not well understood. Among other things, this is due to more labor-intensive and expensive methods for obtaining the starting compounds in comparison with molybdenum counterparts. In this paper, we describe the synthesis of an octahedral cluster complex, (TBA)2[W6Br14] (TBA+ = tetrabutylammonium), in gram quantities, starting from simple substances─W, Br2, and Bi─in 70% yield. The formation of pentanuclear tungsten cluster complexes was recorded as a byproduct. Compounds with substituted terminal ligands (TBA)2[W6Br8Y6] (Y = NO3, Cl, I) were obtained. We also discuss the instability of (TBA)2[W6Br8(NO3)6] under light exposure, the optical properties of a series of compounds (TBA)2[W6Br8Y6] (Y = Cl, Br, I), and the effect of terminal ligands on the chemical shifts in 183W NMR spectra in dimethyl sulfoxide-d6. The presented approach to the synthesis of one of the main precursors of various bromide cluster complexes on a gram scale can stimulate the study of their properties and development of new functional materials based on them.

The family of chalcogenide molybdenum clusters is well presented in the literature by a series of compounds of nuclearity ranging from binuclear to multinuclear articulating octahedral fragments. Clusters actively studied in the last decades were shown to be promising as components of superconducting, magnetic, and catalytic systems. Here, we report the synthesis and detailed characterization of new and unusual representatives of chalcogenide clusters: square pyramidal complexes [{Mo5(μ3-Se)i4(μ4-Se)i(μ-pz)i4}(pzH)t5]1+/2+ (pzH = pyrazole, i = inner, t = terminal). Individually obtained oxidized (2+) and reduced (1+) forms have very close geometry (proven by single-crystal X-ray diffraction analysis) and are able to reversibly transform into each other, which was confirmed by cyclic voltammetry. Comprehensive characterization of the complexes, both in solid and in solution, confirms the different charge state of molybdenum in clusters (XPS), magnetic properties (EPR), and so on. DFT calculations complement the diverse study of new complexes, expanding the chemistry of molybdenum chalcogenide clusters.

Among well-studied and actively developing compounds are polyoxometalates (POMs), which show application in many fields. Extending this class of compounds, we introduce a new subclass of polyoxometal clusters (POMCs) [Mo12O28(μ-L)8]4− (L = pyrazolate (pz) or triazolate (1,2,3-trz or 1,2,4-trz)), structurally similar to POM, but containing binuclear Mo2O4 clusters linked by bridging oxo- and organic ligands. The complexes obtained by ampoule synthesis from the binuclear cluster [Mo2O4(C2O4)2(H2O)2]2− in a melt of an organic ligand are soluble and stable in aqueous solutions. In addition to the detailed characterization in solid state and in aqueous solution, the biological properties of the compounds on normal and cancer cells were investigated, and antiviral activity against influenza A virus (subtype H5N1) was demonstrated.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The substitution of the OH ligand in the trans position to NO in [RuNOPy 2 Cl 2 X] (X = F, OH) results in an increase of thermal stability of RuNO linkage isomers in the solid state, but decreases the quantum yield of the NO release in solution.

The aim of this research was to obtain the grafted copolymer of chitosan with acrylamide using the electron beam irradiation. Radiation dose was varied from 6 to 160 kGy. The highest yield of the product was observed at radiation dose of 12–40 kGy. Further increase in the dose caused a decrease in the product yield as well as its solubility in water. Using gel permeation chromatography, it was confirmed that unreacted chitosan remained in the product. NMR study of the water-soluble part of the product obtained under the doses of 6, 12, and 20 kGy showed that the length of the side chains of grafted acrylamide was about 2 elementary units. Investigation of chitosan solutions by means of dynamic light scattering revealed the presence of chitosan agglomerates in the solution. The possibility of obtaining dense films was demonstrated. Mechanical treatment of the copolymer in the ball mill caused an increase in the solubility of the samples obtained even at radiation doses of 80 and 160 kGy. It was determined by means of chromatographic methods that there were no products with low molecular weight in the ball-milled product, and unreacted chitosan did not undergo mechanocracking during the mechanical treatment.

A simple, one-pot regioselective method for the synthesis of a high-nitrogen tricycle, 2,3,4а,6,7,8а,9,10-octaaza-4,8-dioxo-3,4,4a,7,8,8а,9,9a,10,10а-decahydroanthracene, with a yield of 27% was developed on a starting urea basis as a result of studies focused on finding new, more efficient approaches to the synthesis of high-energy derivatives of dinitramic acid (DNA). This tricycle was further treated to furnish 2,3,4а,6,7,8а,9,10-octaaza-4,8-dioxo-3,4,4a,7,8,8а,9a,10а-octohydroanthracene-9,10-ion-bis(dinitramide). The resultant salt of dinitramic acid exhibited inhibitory properties towards the burning rate of pyrotechnic compositions, reducing it by 30%, and possessed good thermal stability due to a high decomposition temperature above 260 °C and a low sensitivity to mechanical stimuli. The structural features of the new tricycle-based dinitramide salt were characterized via 2D NMR spectroscopy and double-focusing sector mass spectrometry (DFS).

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The formation of vanadium complexes with synthesized enantio- and diastereomerically pure polydentate tetrahydrosalicylidene ligands of the diterpene series was studied using UV, visible, and 51V NMR spectroscopy. The obtained catalyst complexes were tested in the oxidation of prochiral sulfides with an aqueous 35