Showing papers by "Andrei V. Churakov published in 2014"

Pharmaceutical Cocrystals of Diflunisal and Diclofenac with Theophylline

Abstract: Pharmaceutical cocrystals of nonsteroidal anti-inflammatory drugs diflunisal (DIF) and diclofenac (DIC) with theophylline (THP) were obtained, and their crystal structures were determined. In both of the crystal structures, molecules form a hydrogen bonded supramolecular unit consisting of a centrosymmetric dimer of THP and two molecules of active pharmaceutical ingredient (API). Crystal lattice energy calculations showed that the packing energy gain of the [DIC + THP] cocrystal is derived mainly from the dispersion energy, which dominates the structures of the cocrystals. The enthalpies of cocrystal formation were estimated by solution calorimetry, and their thermal stability was studied by differential scanning calorimetry. The cocrystals showed an enhancement of apparent solubility compared to the corresponding pure APIs, while the intrinsic dissolution rates are comparable. Both cocrystals demonstrated physical stability upon storing at different relative humidity.

New oligogermane with a five coordinate germanium atom: the preparation of 1-germylgermatrane

Abstract: The first example of an oligogermane, N(CH2CH2O)3Ge–Ge(SiMe3)3 (1), containing a hypercoordinate germanium atom was prepared and characterized by various methods (NMR, UV/vis, and X-ray analysis). The electronic structure of compound 1 was investigated via DFT calculations.

Structures of monomeric octahedral d 2 rhenium(V) oxo complexes with oxygen atoms trans to the oxo ligands: Complexes with methoxo ligands trans to O(oxo)

Abstract: Specific features of the structure of mononuclear octahedral rhenium(V) complexes with oxygen atoms of ethoxo ligands trans to the multiply bonded oxo ligands have been considered The complexes contain inorganic or organic monodentate ligands, as well as organic bi-, tri-, and tetradentate ligands in the equatorial plane It has been noted that the Re-O(OEt) trans bonds, like the other bonds with alkoxy ligands ORalk (in particular, Re-O(OMe trans )) are not elongated owing to the structural manifestation of the trans influence of multiply bonded oxo ligands; rather, they are significantly shortened This fact is explained by that the Re-O(ORalk) bonds are also multiple; ie, the oxo alkoxo complexes should been considered as pseudo-dioxo compounds Re(=O)(=ORalk)

New supramolecular synthons based on 3d transition metal complexes with bidentate bispidines: synthesis and structural, spectroscopic, and electrochemical studies*

Abstract: A new supramolecular synthon, a 2L: 1M complex of bidentate bispidine with transition metal, was suggested. A number of complex compounds of 1,5-dimethylbispidin-9-one with Cu ii , Ni ii , and Co ii salts (perchlorates, chlorides, bromides, nitrates, trifluoroacetates) were synthesized. The structure and composition of complexes obtained were estimated based on the combination of physicochemical methods of analysis (elemental analysis, X-ray diffraction analysis, NMR, IR, and Raman spectroscopy, electron absorption spectroscopy, ESI mass spectrometry, CVA). The composition of most complexes in the solid state corresponds to the formula ML2X2, and in a number of cases the fragment [ML2]2+ is retained in solution, which was shown by NMR spectroscopy for nickel complexes and by mass spectrometry for copper complexes. In the case of copper chloride, the composition of the acetonitrile solutions in the presence of the ligand depends on the ratio of starting compounds and their concentration: an increase in proportion of CuCl2 and concentration shifts the equilibrium to the side of complexes with higher nuclearity. A 2L: 1M complex of bispidine with metal was for the first time structurally characterized using copper(ii) nitrate derivative as an example. The CVA method showed existence of reversible electrochemical reduction of the metal for a number of complexes (the products of the reaction of 1,5-dimethylbispidin-9-one with nickel(ii) and cobalt(ii) chlorides, as well as with nickel(ii) bromide). According to the IR and Raman spectra, chelation of metals with 1,5-dimethylbispidin-9-one leads to the shift of the absorption band of the ligand carbonyl group from 1700 to 1721–1744 cm−1. Nickel(ii) and copper(ii) perchlorates and nitrates were concluded to be the most promising complexation agents for the binding of two NH,NH-bispidine ligands in a coordination polymer.

Reaction of digermanes and related Ge-Si compounds with trifluoromethanesulfonic acid: synthesis of helpful building blocks for the preparation of Ge-Ge(Si)-catenated compounds

Abstract: Abstract The reaction of a series of compounds, Ar3 Ge-MR3, 1–4 (Ar=Ph, p-Tol, M=Si, Ge, R=Ph, Me, tBu), with one equivalent of trifluoromethanesulfonic acid (HOTf) was investigated. The corresponding triflates were isolated in several cases. The molecular structure of Ph3 Ge-GePh2 OTf (5) in solid state was investigated by X-ray analysis. The triflates were converted to the corresponding chlorides under the action of ammonium chloride.

Influence of the anion nature on styryl dye crystal packing and feasibility of the direct and back [2 + 2] photocycloaddition reactions without single crystal degradation

Abstract: A family of styryl dyes of the 4-pyridine series, Et–Py+–CHCH–C6H3(OMe)2 X−, with different anions X−, was synthesized. Their ability to undergo [2 + 2] photocycloaddition (PCA) in the polycrystalline state with the formation of 1,2,3,4-tetrasubstituted rctt cyclobutanes under irradiation with visible light was investigated by 1H NMR spectroscopy. Crystal packing of the dyes and feasibility for the PCA reaction in single crystals were investigated by X-ray structural analysis. Small inorganic anions, such as ClO4−, BF4−, PF6− that do not form secondary interactions with the organic cation, aid the formation of cation stacking motifs of the “head-to-tail” type. In these stacks, any adjacent cations are arranged in an antiparallel fashion and approach one another at distances shorter than 4.2 A, which corresponds to the Schmidt's rule for feasibility of PCA reaction in the solid state. As a result of PCA, rctt isomers of cyclobutane derivatives are formed. Success of the PCA reaction without single crystal degradation was only found for the dye containing BF4− anion. Upon irradiation with UV light of the cyclobutane product formed in the crystal, back phototransformation without single crystal degradation was observed. A number of weak interactions I−⋯H–C in the dye with I− anion prevent significant atomic displacements that accompany the PCA transformation from being achieved. Occurrence of the bulky tosylate anion forming a set of hydrogen bonds with solvate acetonitrile and water molecules aids the formation of “head-to-head” type stacks, with a large separation between the adjacent ethylene bonds. In the dye containing bulky BPh4− anion, the main structure-forming role belongs to anions, which suppress the cation trend to form a stacking packing motif. The dye with picrate anion forms two types of crystals. Crystal packing of one of them excludes any PCA transformation, whereas, the other one permits it, but with single crystal degradation.

Specific features of the structure of monomeric octahedral d 0-rhenium(VII) oxo complexes

Abstract: The specific structural features of mononuclear octahedral oxo complexes of rhenium(VII) are considered. The crystal structures of mono- and dioxo complexes d 0-Re(VII) with one or two multiply bonded (=N,=C) organic ligands, di- and trioxo compounds, and pseudooctahedral trioxo complexes ReO 3 + with cyclopentadienyl and its derivatives are analyzed.

Group 5 hydride and borohydride complexes supported by cyclopentadienyl-imido ligand sets

Abstract: Reactions of Cp*Ta(NAr)Cl2 and CpM(NAr)Cl2 (M = Nb, Ta; Ar = 2,6-C6H3iPr2) with NaBH4 in the presence of an excess of PMe3 provided facile access to the corresponding dihydride derivatives CpRM(NAr)H2(PMe3) (CpR = Cp, Cp*). Reaction of Cp*Nb(NAr)Cl2 with NaBH4 in the absence of phosphine gave the Nb(+5) borohydride–hydride complex Cp*Nb(NAr)H(η2-BH4). When the corresponding reactions for CpM(NAr)Cl2 (M = Nb, Ta) were carried out in the absence of an excess of phosphine, dimeric MIV products [CpM(μ-NAr)(η2-BH4)]2 containing M–M single bonds were formed.

Electrochemical and chemical synthesis and structure of adducts (CH3OH and H2O) of metal chelates of N,N,O tridentate pyrazole-containing Schiff base

Abstract: Chemical and electrochemical synthesis of a series of cobalt(II), nickel(II), copper(II), and zinc(II) complexes of tridentate Schiff base (H2L), a product of condensation of N-(2-aminophenyl)-4-methylbenzenesulfonamide (2-tosylaminoaniline) with 1-phenyl-3-methyl-4-formylpyrazol-5-ol was accomplished. The structure and composition of metal-chelates were established by the C, H, N elemental analysis, IR, 1H NMR, EXAFS spectroscopy and magnetochemical data. The structures of all complexes were confirmed by of X-ray crystallography.

Synthesis, crystal structure, and electroluminescent properties of zinc and cadmium tetradentate azomethine complexes

Abstract: Chemical and electrochemical syntheses of zinc(II) and cadmium(II) complexes based on tetradentate Schiff bases (H2L1 and H2L2) resulting from condensation of 2-tosylaminobenzaldehyde with 3,6-dioxa-1,8-octanediamine or 4,9-dioxa-1,12-dodecanediamine were performed. The structure, composition, and properties of the complexes were studied by elemental analysis, IR, 1H NMR, and UV spectroscopy, X-ray absorption spectroscopy, and X-ray diffraction. The zinc(II) and cadmium(II) complexes luminesce in a DMF solution in the blue spectral region (λPL = 425–433 nm), the photoluminescence quantum yield φ being 0.25–0.30. Multilayer zinc(II)- and cadmium(II)-based electroluminescent structures with green-blue emission of the exciplex nature were fabricated.

Synthesis, structure, and catalytic activity of new aluminum complexes formed with sterically bulky ligands

Abstract: A reaction of pyridine related ligands containing two hydroxyalkyl groups, 2,6-(HO-Z-CH2)2C5H3N (Z is 1,1-cyclohexylene, 2,2-adamantylene) with trimethylaluminum and trimethoxyaluminum leads to three new aluminum complexes with the Me-Al or MeO-Al bond: 2,6-C5H3N(CH2-Z-O)2Al-X (Z is 1,1-cyclohexylene, X = Me (5), OMe (6); Z is 2,2-adamantylene, X = Me (7)). The structures of new derivatives were confirmed by NMR spectroscopy and elemental analysis. The structure of complex 5 was studied by X-ray diffraction analysis. Complex 5 is a dimer in the solid state due to the formation of a four-membered ring...Al-O...Al-O.... Complexes 5 and 6 were studied as initiators of the ring-opening polymerization of e-caprolactone.

Specific features of the structures of d 2 -Rhenium(V) monomeric octahedral oxo complexes: I. Structure of d 2 -Re(V) mono-oxo compounds with halogen ligands trans-positioned to O(oxo) ligands

Abstract: The specific features of the structure of rhenium(V) mononuclear octahedral mono-oxo complexes with halogen ligands (F, Cl, Br), trans-positioned to multiply bonded oxo ligands, are considered.

Synthesis and crystal and molecular structure of the [MoO 2 ( L )(H 2 O)] · H 2 O complex ( L 2− is the anion of 2-[ N -(hydroxynaphtylidene)amino]propan-1,2,3-triol)

Abstract: A new compound of dioxomolybdenum(VI)—[MoO2(L)(H2O)] · H2O, where L 2− = 2-[N-(hydroxynaphtylidene)amino]propan-1,2,3-triol)—is synthesized. Its structure is determined by X-ray diffraction. The Mo atom has an octahedral coordination formed by two oxo ligands located cis with respect to one another, two O atoms and the N atom of the tridentate bis(chelate) L 2− ligand, and the O atom of a water molecule. The crystallization water molecule is connected with two complex molecules by O-H…O hydrogen bonds.

Reaction between uranyl dihydroxylaminate and benzaldehyde

Abstract: Reactions of coordinated ligands in uranyl hydroxylaminate complexes with benzaldehyde were studied. Methods of the synthesis of uranyl complexes containing E and Z isomers of benzaldehydoxime were developed. The structures of [UO2((E)-C7H6NO)2{(CH3)2SO}2] and [UO2((Z)-C7H6NO)2{(CH3)2SO}2] were determined by X-ray diffraction.

Features of cation packing in crystal forms of a 18-crown-6-containing styryl dye iodide and feasibility of the solid phase [2+2]-autophotocycloaddition reaction in it

Abstract: X-ray structure determinations of three crystal forms of a 18-crown-6-containing styryl dye of the pyridine series in iodide form (1), containing various solvate molecules, namely water (1a), 2,6-dihydroxyoaphthalene (1b), 1,4-hydroquinone (1c), and analysis of crystal packings of these crystals, together with the previously investigated non-solvated form (crystal 1) and the solvates with benzene and water (crystal 1d) has been carried out. Crystal packing in 1a, 1b, 1c, and 1d involves a stacking leading to dimers of the dye cations, structurally preorganized for the [2+2]-photocycloaddition (PCA) reaction. On irradiation of with visible light, the PCA reaction with the centrosymmetric rctt isomer leads to the cyclobutane derivative formation. In the case of 1a and 1b the PCA proceeds with the retention of crystallinity, while with other solvates crystals are transformed into a glass. The glasses keep the form and the shine of the initial crystals, nevertheless. In the cases of the non-solvated crystal form (1), translation-related stacks form, with the geometry inconsistent with that of the preorganized dimer. These crystals are stable in visible light.

Binuclear complex of silver(I) perrhenate with phthalazine: Synthesis, crystal structure, and luminescence properties

Abstract: Silver compound Ag2(Phtz)4](ReO4)2 (I) (Phtz is phthalazine, C8H6N2) is synthesized, and its crystal structure is determined. The crystals are triclinic: space group \(P\bar 1\), a = 9.651(2), b = 9.655(2), c = 10.884(2) A, α = 115.752(2)°, β = 94.582(2)°, γ = 106.000(2)°, V = 854.3(2) A3, Z = 1, ρcalcd = 2.404 g/cm3. The Ag atom forms a triangular coordination mode (Ag(1)-N(11) 2.34(2), Ag(1)-N(12A) 2.24(2), and Ag(1)-N(21) 2.28(1) A) by the nitrogen atoms of one monodentate and two bridging phthalazine molecules. Their interaction results in the formation of an almost planar centrosymmetric binuclear cationic complex [Ag2(Phtz)4]2+ (Ag(1)⋯Ag(1A) 3.452(7) A). The oxygen atoms of the ReO4− anion are randomly disordered over three positions each. The luminescence spectrum contains an emission band in the green region.

Crystal structure of ammonium succinate peroxosolvate

Abstract: The crystal structure of previously unknown ammonium succinate peroxosolvate is studied. It is shown that it represents a rare example of the structure where H2O2 molecule forms two donor hydrogen bonds and does participate in any acceptor hydrogen bonds, despite the presence of substantial quantity of nonperoxide active hydrogen atoms.

Crystal structure of a mixed-valence μ-oxide Sn12 cluster.

Abstract: The mixed-valence μ-oxide Sn12 cluster, deca­carbonyl­tetra-μ4-oxido-hexa-μ3-oxido-tetra­kis­[μ-2,2′-(pyridine-2,6-di­yl)bis(1,1-di­phenyl­ethano­lato)]deca­tin(II)ditin(IV)dimolyb­denum(O)(2 Mo—Sn) toluene hepta­solvate, [Mo2Sn12(C33H27NO2)4O10(CO)10]·7C7H8, has a crystallographically imposed inversion centre. The asymmetric unit also contains three and a half toluene solvent mol­ecules, one of which is disordered about a centre of symmetry. The complex mol­ecule comprises six distinct Sn atom species with four different coordination numbers, namely 3, 4, 5, and 6. The SnII atoms forming the central Sn10O10 core adopt distorted trigonal–pyramidal, square-pyramidal and octa­hedral coordination geometries provided by the μ-oxide atoms and by the O- and N-donor atoms of two pyridinedi­ethano­late ligands. The terminal SnIV atoms have distorted trigonal–bipyramidal coordination geometries, with a μ4-oxide atom and the N atom of a pyridinedi­ethano­late ligand occupying the axial positions, and the Mo atom of a Mo(CO)5 group and the alk­oxy O atoms of a ligand forming the equatorial plane. In the crystal, weak intra- and inter­molecular C—H⋯O hydrogen bonds are observed.

Crystal and molecular structure of diaquadinitratouranyl dihydrate [UO2(NO3)2(H2O)2] · 2H2O

Abstract: Single crystals of previously unknown diaquadinitratouranyl dihydrate [UO2(NO3)2(H2O)2] · 2H2O (I) were obtained by evaporation of aqueous solution of [UO2(NO3)2(H2O)2] · 4H2O containing nitric acid in air at ambient temperature. The structure of the complex was studied by X-ray diffraction analysis. Crystals are monoclinic, a = 7.6820(15) A, b = 9.887(2) A, c = 7.1990(14) A, β = 105.08(3)°, space group P21/c, Z = 2, V = 527.95(18) A3. Structural units of crystal are neutral centrosymmetrical molecular complexes [UO2(NO3)2(H2O)2] and crystal water molecules united by a hydrogen bond system. Certain structural and spectral characteristics of new complex I and known diaquadinitratouranyl complexes were compared.

Reactions of 2-cyano-3-ferrocenylacrylonitrile with malononitrile: formation of 4-ferrocenylpyridine-3,5-dicarbonitrile derivatives and sodium polymeric complexes containing carbanionic ligands

Abstract: Abstract The reactions of 2-cyano-3-ferrocenylacrylonitrile with malononitrile in a EtOH/H2O or MeOH/H2O medium in the presence of Na2CO3 afforded 6-alkoxy-2-amino-4-ferrocenylpyridine-3,5-dicarbonitriles 3a,b (multi-component condensation), 6-alkoxy-2-amino-4-ferrocenyl-3-ferrocenylmethyl-3,4-dihydropyridine-3,5-dicarbonitriles 4a,b (multi-component cyclodimerization) and Na+ polymeric complexes: {[Na+(2-ferrocenyl(tetracyano)propenyl)–L]∞5a,b and [Na+(2-amino-3,5-dicyano-4-ferrocenyl-6-pyridyl-dicyanomethyl)–L]∞6a,b, where L = ethanol, methanol. Complexes with L = acetonitrile, dimethylformamide, acetone, ethyl acetate were prepared by recrystallization. The structures of the compounds 3b, 4b and Na+ polymeric complexes were established by the spectroscopic data and X-ray diffraction analysis. Two compounds 3a and 4a were tested in vitro against six human tumor cell lines U-251, PC-3, K-562, HCT-15, MCF-7 and SKLU-1 to assess their in vitro antitumor activity. The results suggest biological specificity towards PC-3, K-562 and HCT-15 cells for compound 3a, and towards PC-3 cell for compound 4a at doses of 50 μM, which are lower than cis-platin.

Pd17In4Se4, a Metal‐Rich Palladium—Indium Selenide with an Open‐Framework Structure.

Abstract: Needle-like crystals of the new title compound are synthesized from a mixture of the elements in a ratio of Pd:In:Se = 7:2:1 (silica ampule, 750 °C, 7—10 d).

Transfer of the chelating ligands in the systems [LAuCl2]+-[PdCl4]2−: Synthesis and structure of the salt (NH4)0.20[(Bipy)AuCl2]1.04[(Bipy)PdCl2]0.96[AuCl4]0.76[PdCl4]0.24

Abstract: The formation of binary complex salts containing gold(III) in the cation and palladium(II) in the anion in the systems [(Bipy)AuCl2]+-[PdCl4]2− occurs by transfer of the N,N-electron-donating chelating ligand bipyridine and the chloride ligands between the gold-containing cation and the palladium-containing anion. The resulting neutral salt [(Bipy)PdCl2] crystallizes together with the anion [AuCl4]− from acetonitrile-water (1 : 1-1 : 2, v/v) to give the complex salt (NH 4 + )0.20[(Bipy)AuCl 2 + ]1.04[(Bipy)PdCl2]0.96[AuCl 4 − ]0.76PdCl 4 2− ]0.24 with a total Au : Pd ratio of 3 : 2. The ammonium cation is formed from acetonitrile upon its hydrolysis most likely catalyzed by Pd complexes. Quantum-chemical calculations were performed to study the transfer of the chelating ligand theoretically.