Showing papers in "Russian Chemical Bulletin in 2004"

Thienopyridines: synthesis, properties, and biological activity

Abstract: The current state and prospects of development of the chemistry of isomeric thienopyridines (synthesis, chemical transformations, and biological activities) are analyzed. Particular attention is given to studies published in the last 10–15 years.

Boron and gadolinium neutron capture therapy

Abstract: The principles of neutron capture therapy of tumor diseases, the types of drugs, and the results of their clinical applications are discussed.

Spin transitions in non-classical systems

Abstract: Peculiarities of synthesis of chain polymeric, copper(II) hexafluoroacetylacetonate based complexes with stable nitroxyl radicals and the results of studies on correlations between the magnetic properties and structure of these compounds are summarized. Temperature variation causes structural rearrangements in the solid phases of the compounds, accompanied by the magnetic effects similar to spin crossover phenomena. Magnetic anomalies induced by phase transitions originate from specific motions in the Jahn—Teller coordination units containing two types of exchange clusters, Cu2+—O·—N N—·O—Cu2+—O·—N<, and are accompanied by significant changes in the crystal volume after multiple cooling/heating cycles. Chemical methods of controlling the character and temperature of spin transitions by both the formation of solid solutions of mixed metal hexafluoroacetylacetonates with the same nitroxyl radical, {Cu1−xMx(hfac)2L} (M = Mn, Ni, Co), and by the formation of solid solutions based on copper(II) hexafluoroacetylacetonate with different nitroxyl radicals, {Cu(hfac)2LxL′1−x}, are discussed. Specific influence of isotope substitution CH3 → CD3 in the paramagnetic ligand on both the structure of the heterospin polymer chain and the temperature of the magnetic anomaly is discussed.

Spintronics and spintronics materials

Abstract: The review concerns the fundamentals of spintronics (spin-transport electronics) The material covers spin-spin interactions and spin relaxation in semiconductors as well as spin and spin injection related effects in the condensed matter Examples of promising spintronic devices are given, requirements for spintronic materials are formulated, methods of synthesis of spintronic materials are described, and the physicochemical properties of some materials are characterized Organic spintronic materials are briefly outlined and the state-of-the art in the field of research on inhomogeneous magnetic semiconducting materials possessing high-temperature ferromagnetism is described The emphasis is placed on the chemical bonding and electronic structure of magnetic impurities in semiconductors, consideration of the nature of ferromagnetism, and on the character of exchange interactions between localized spins in novel spintronic materials

Protonation of magnesium and sodium complexes containing dianionic diimine ligands. Molecular structures of 1,2-bis{(2,6-diisopropylphenyl)imino}acenaphthene (dpp-BIAN), [(dph-BIAN)H2(Et2O)], and [(dpp-BIAN)HNa(Et2O)]

Abstract: Hydrolysis of magnesium complexes containing the dianionic acenaphthenediimine ligands, (dpp-BIAN)Mg(thf)3 (1), (dph-BIAN)Mg(thf)3 (2), and (dtb-BIAN)Mg(thf)2 (3) (dpp-BIAN is 1,2-bis{ (2,6-diisopropylphenyl)imino}acenaphthene; dph-BIAN is 1,2-bis{(2-diphenyl)imino}acenaphthene; dtb-BIAN is 1,2-bis{(2,5-di-tert-butylphenyl)imino}acenaphthene), affords the corresponding diamines (dpp-BIAN)H2 (4), (dph-BIAN)H2(Et2O) (5), and (dtb-BIAN)H2 (6). Compounds 4 and 5 were isolated in the crystalline state and characterized by UV-Vis, IR, and 1H NMR spectroscopy. Partial hydrolysis of (dpp-BIAN)Na2(Et2O)3 gave the crystalline (dpp-BIAN)HNa(Et2O)2 complex (7), which was also characterized by spectroscopic methods. The structures of compounds 5 and 7 and free diimine dpp-BIAN were established by X-ray diffraction analysis.

Modeling of self-organization processes in crystal-forming systems. Structural mechanism of self-assembly of zirconosilicate Na2ZrSi2O7 from suprapolyhedral clusters

Abstract: Topological analysis of the crystal structure of Na2ZrSi2O7 (parakeldyshite, space group P1–) with an MT framework, where M are ZrO6 octahedra and T are SiO4 tetrahedra, was carried out by the method of coordination sequences (TOPOS.3.2 program package), and the self-organization of this structure was modeled. The cyclic-type suprapolyhedral cluster precursor Na2M2T4 with the local symmetry 1– was identified by bicolor decomposition of the 4646+664 net. The cluster is composed of six polyhedra with two Na atoms located in the center. The precursors control the evolution of high-level crystal-forming clusters. The cluster coordination number is six. The centers of eight cluster precursors in the superprecursor of the Na2ZrSi2O7 structure are related by translation vectors.

Crystal structures and excimer fluorescence of anisoylbenzoylmethanatoboron and dianisoylmethanatoboron difluorides

Abstract: The crystal structures and spectral-luminescence properties of anisoylbenzoylmethanatoboron difluoride (1) and dianisoylmethanatoboron difluoride (2) were studied in the solid state and in solution. The structural features of compounds 1 and 2 are responsible for the occurrence of a new type of excimers in solutions, which differs from that observed in the crystalline state.

Synthesis and study of the properties of the homologous series of polyallylcarbosilane dendrimers and their nonfunctional analogs

Abstract: A synthetic route combining the preparation of functional and nonfunctional carbosilane dendrimers has been developed Using this route, two representative homologous series of carbosilane dendrimers have been prepared The use of nonfunctional dendrimer derivatives ensures the possibility of performing long-term experiments both in solution and in the bulk The intrinsic viscosity and the density of the specimens studied do not depend on the generation number The obtained dendrimers of later generations were studied by atomic force microscopy and light scattering

Alkylation of carboxylic acid derivatives with dialkoxytitanacyclopropane reagents

Abstract: Methods for the generation of dialkoxytitanacyclopropanes (dialkoxytitanium olefin complexes) are surveyed. Alkylation of carboxylic acid derivatives with these reagents giving rise to β-titanio ketones and related species, which are spontaneously transformed into the corresponding cyclopropane compounds or react with external electrophiles, are considered.

Catalytic olefination of carbonyl compounds. A new versatile method for the synthesis of alkenes

Abstract: The review is devoted to a new catalytic olefination reaction (COR) discovered by the authors. This is the reaction between N-unsubstituted hydrazones of carbonyl compounds with dihalides CHal2XY in the presence of copper(i) chloride to give substituted alkenes. Catalytic olefination is versatile. Variation of the carbonyl and olefinating components opens up the way for the synthesis of various classes of unsaturated compounds including those containing functional groups. The reaction mechanism is discussed and a catalytic cycle describing the process is proposed. A model for estimating and predicting the reactivity of halogen-containing compounds in the COR is developed. The relationship between the structure of the carbonyl substrates and their behavior in the title reaction is elucidated.

Structure—property modeling of metal binders using molecular fragments

Abstract: The method of Substructural Molecular Fragments (SMF) based on splitting of a molecular graph into a limited number of topological fragments and calculation of their contributions to a given property was applied to the structure—property modeling of (i) stability constants of the complexes formed by the K+ cation with phosphoryl-containing podands in a mixed THF—CHCl3 solvent, (ii) distribution coefficients for Hg and Pt extraction by podands from water into 1,2-dichloroethane, and (iii) stability constants of complexes of crown ethers with alkali metal cations in methanol. A procedure for the reduction of the number of fragment descriptors in structure—property relationship (QSPR) models based on the Student t-test was proposed. The use of selected variables improves the robustness of the structure—property models.

New oxidative transformations of alkenes and alkynes under the action of diacetoxyiodobenzene

Abstract: Treatment of alkenes and alkynes with diacetoxyiodobenzene activated by mineral and organic acids predominantly results in oxidative rearrangement. 1,4-Diphenylbutadiene in MeOH gives 3,4-dimethoxy-1,4-diphenylbut-1-ene.

Reactions of (dpp-BIAN)Mg(thf) 3 complex (dpp-BIAN is 1,2-bis{(2,6-diisopropylphenyl)imino}acenaphthene) with halogen-containing reagents

Abstract: The reactions of the acenaphthenediimine complex (dpp-BIAN)Mg(thf)3 (1) (dpp-BIAN is 1,2-bis{ (2,6-diisopropylphenyl)imino}acenaphthene) with various chlorine-, bromine-, and iodine-containing reagents afforded the unsymmetrical compounds [(dpp-BIAN)MgCl(thf)]2 (6), [(dpp-BIAN)MgBr(thf)]2 (7), and (dpp-BIAN)MgI(DME) (8). The reaction of complex 1 with Me3SiCl in THF is accompanied by the cleavage of the THF molecule to form [{dpp-BIAN(CH2)4OSiMe3}MgCl]2 (9), in which the trimethylsilanyloxybutyl group is bound to one of the carbon atoms of the diimine fragment. The reaction of complex 1 with Me2NCH2CH2Cl in THF produces the [dpp-BIAN(H)(CH2)2NMe2] compound (10) containing no magnesium. Paramagnetic complexes 6–8 were characterized by ESR spectroscopy. Diamagnetic compounds 9 and 10 were studied by 1H and 13C NMR spectroscopy. The molecular structures of complexes 6–10 were established by X-ray diffraction analysis. In the crystalline state, compounds 6, 7, and 9 exist as halogen-bridged dimers. In all magnesium derivatives, BIAN serves as a chelate ligand.

Metabolites of the marine fungus Humicola fuscoatra KMM 4629

Abstract: A new sesquiterpene of the caryophyllene series, fuscoatrol A (1), and known compounds, 11-epiterpestacin (2) and β-nitropropionic acid (3), were isolated from the marine fungus Humicola fuscoatra (Traaen) KMM 4629 associated with the Kuril colonial ascidium. The structure of 1 was established on the basis of X-ray diffraction data and 2D NMR spectroscopy. The antimicrobial and cytotoxic activities of compounds 1–3 were studied.

Functional models of [Fe—S] nitrosyl proteins

Abstract: The review surveys methods for the synthesis, as well as structures and properties of sulfur-containing iron nitrosyl complexes serving as models of active sites of [Fe—S] nitrosyl proteins, which are potential donors of nitrogen monoxide.

Magnesium and calcium complexes with two diimine radical-anion ligands. Molecular structure of the Ca complex with 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene

Abstract: Four- and five-coordinate magnesium and calcium complexes containing two diimine radical-anion ligands with compositions (dpp-BIAN)2Mg (1), (dpp-BIAN)2Ca (2), (dtb-BIAN)2Mg (3), and (dtb-BIAN)2Ca(THF) (4) (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene and dtb-BIAN is 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene) were synthesized. At 120 K, the ESR spectra of complexes 1–4 in a toluene matrix show signals characteristic of biradical derivatives. The molecular structure of compound 2 was established by X-ray diffraction analysis. At 293 K, the magnetic moments of compounds 1, 2, 3, and 4 are 2.55, 2.57, 2.76, and 2.79 μB, respectively, which are indicative of the presence of two unpaired electrons localized on the ligands.

Divalent silicon, germanium, and tin compounds with element--heteroatom bonds

Abstract: Principal results and trends in chemistry of organic derivatives of divalent silicon, germanium, and tin containing bonds between these elements and the halogen, nitrogen, oxygen, and sulfur atoms are briefly surveyed. Selected characteristics of compounds with the element--phosphorus and element--arsenic bonds are discussed for comparison. Data on the synthesis and structures of new types of these compounds, viz., germanium(ii) diacylates, the alkoxy derivatives E14(OR)2 and E14(OR)Y (E14 = Ge, Sn; R = Me2NCH2CH2; Y = Cl, AcO, (Me3Si)2N), and the ate-complexes Li(+)[E14(OCH2CH2NMe2)3](–) and [Li(thf)2](+)[TsiE14(SBu)2](–) (E14 = Ge, Sn; Tsi = (Me3Si)3C), are presented. It was established for the first time that germanium(ii) and tin(ii) derivatives can be stabilized in the monomeric form only through the intramolecular Nsp3→E14 coordination bonds and the σ-acceptor effect of the oxygen atoms without introduction of bulky substituents.

Arene complexes [(η-C5H5)M(η-C6R6)]2+ (M = Rh, Ir)

Abstract: The dicationic arene complexes [CpM(arene)](BF4)2 (arene = C6H6, 1,3,5-C6H3Me3, or C6Me6) were synthesized by the reactions of the solvated complexes [CpM(MeNO2)3](BF4)2 (M = Rh, Ir) with benzene and its derivatives. The solvated complexes were generated in situ by abstraction of I− from [CpMI2]2 with AgBF4. A procedure was developed for the synthesis of the iodide [CpRhI2]2 based on the reaction of the cyclooctadiene derivative CpRh(1,5-C8H12) with I2. The structure of the [CpRh(C6Me6)](BF4)2 complex was established by X-ray diffraction analysis.

Synthesis of dendrimers with terminal formyl groups

Abstract: A method for preparation of dendrons and dendrimers with formyl groups at the terminal aromatic rings, ether bonds in the branching blocks, and ester bonds in the core of the macromolecules is proposed. A way for the selective synthesis of p-hydroxymethylbenzaldehyde is described.

Synthesis of secondary and tertiary aminofurazans

Abstract: Reactions of nitrofurazans with primary and secondary amines were studied. Conditions were found which allow the efficient replacement of the nitro group with these nucleophiles. Transformations of the amidoxime fragment, which is bound to the furazan ring and contains an amino substituent, enable one to substantially expand the spectrum of polyfunctional derivatives. The structures of the amines synthesized were studied by X-ray diffraction analysis.

Syntheses and crystal structures of supramolecular compounds of tetranuclear ZrIV and HfIV aqua hydroxo complexes with macrocyclic cavitand cucurbituril

Abstract: Slow evaporation of hydrochloric acid solutions of zirconium(iv) or hafnium(iv) oxochlorides and cucurbituril in air afforded compounds with composition [M4(OH)8(H2O)16]Cl8·(C36H36N24O12)·16H2O, where M = Zr (1) or Hf (2). According to the X-ray diffraction data, complexes 1 and 2 are isostructural. Their crystal structures can be described as packings of polymer chains consisting of alternating cucurbituril molecules and tetranuclear cations [M4(OH)8(H2O)16]8+ linked to each other via an extensive network of hydrogen bonds. Compound 2 is the first structurally characterized tetranuclear hafnium aqua complex.

Ring contraction in reactions of 3-benzoylquinoxalin-2-ones with 1,2-phenylenediamines. Quinoxaline-benzoimidazole rearrangement

Abstract: The reactions of 3-benzoylquinoxalin-2-one and its N(1)-alkyl derivatives with 1,2-phenylenediamines were accompanied by ring contraction as a result of the quinoxaline-benzoimidazole rearrangement giving rise to 2-benzoimidazolyl-substituted quinoxalines. The possible pathways of these reaction are discussed.

Synthesis of isomeric 3-phenyl-5-(pyridylmethylene)-2-thiohydantoins and their S-methylated derivatives. Molecular and crystal structures of (5Z)-3-phenyl-5-(pyridin-2-ylmethylene)-2-thiohydantoin and (5Z)-2-methylthio-3-phenyl-5-(pyridin-2-ylmethylene)-3,5-dihydro-4H-imidazol-4-one

Abstract: Three procedures were used for the synthesis of α-, β, and γ-pyridyl-substituted (5Z)-3-phenyl-5-(pyridylmethylene)-2-thiohydantoins: the reaction of 2-thiohydantoin with the corresponding aldehyde in AcOH in the presence of AcONa, the two-step one-pot synthesis with the use of the same starting compounds, and three-component condensation of aryl isothiocyanate, glycine, and aldehyde in AcOH. Alkylation of the resulting thiohydantoins with iodomethane in the presence of a base afforded the corresponding S-methylated derivatives, viz., 2-methylthio-3-phenyl-5-(pyridylmethylene)-3,5-dihydro-4H-imidazol-4-ones. The structures of (5Z)-3-phenyl-5-(pyridin-2-ylmethylene)-2-thioxoimidazolin-4-one and (5Z)-2-methylthio-3-phenyl-5-(pyridin-2-ylmethylene)-3,5-dihydro-4H-imidazol-4-one were established by X-ray diffraction analysis.

Formation, properties, and thermal decomposition of bisarene chromium(i) and molybdenum(i) fullerides

Abstract: Fullerides [(η6-Ph2)2Cr]+[C60]·−, [(η6-C10H12)2Cr]+[C60]·− (C10H12 is tetralin), and [(η6-PhCH3)2Mo]+[C60]·− were synthesized. The molecular structure of [(η6-Ph2)2Cr]+[C60]·− was established. In this compound at 100 K, radical anions C60 −· are linked by an ordinary bond to form dimers, whereas at 293 K they are disordered and do not form dimers. The [(η6-tetralin)2Cr]+[C60]·− fulleride is stable in vacuo (10−2 Torr) below 429 K, and [(η6-toluene)2Mo]+[C60]·− is stable below 581 K.

Synthesis of new stereoregular 2,4,6,8-tetraphenylcyclotetrasiloxanes with mesogenic groups and the influence of spatial isomerism on the phase state of individual isomers and their mixtures

Abstract: The hydrosilylation of four isomers of tetra(dimethylsiloxy)tetraphenylcyclotetrasiloxane with (4′-cyanobiphenyl-4-yl)undec-10-enoate in the presence of a platinum catalyst afforded four liquid-crystalline stereoisomers of phenylcyclotetrasiloxane with mesogenic cyanobiphenyl groups. The reaction was performed for the first time. The influence of the spatial structure of the stereoisomers of tetraphenylcyclotetrasiloxanes with mesogenic groups on the formation of the liquid-crystalline state by thermooptical, X-ray diffraction, and calorimetric methods. The temperatures and enthalpies of phase transitions were determined, and their reversibility was shown. Differences in both the textures of melts formed on cooling and the phase state and in interplanar distances were found by optical microscopy and X-ray diffraction methods. Based on these data, the spatial structure of the isomers was concluded to affect the phase composition and type of packing in the liquid-crystalline state.

Inclusion of nickel(II) and copper(II) complexes with aliphatic polyamines in cucurbit[8]uril

Abstract: The inclusion compound of macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex containing the tetraazamacrocyclic ligand cyclam, {[Ni(cyclam)]@CB[8]}Cl2··16H2O (1), and the inclusion compounds of CB[8] with the copper(II) bis-ethylene-diamine complex, {trans-[Cu(en)2(H2O)2]@CB[8]}Cl2·{CB[8]}·42H2O (2a) and {trans-[Cu(en)2(H2O)2]@CB[8]}Cl2·17H2O (2b), were synthesized and characterized by X-ray diffraction analysis, IR and ESR spectroscopy, and electrospray mass spectrometry. Guest—host inclusion compounds can be directly synthesized starting from a metal complex and cucurbit[8]uril, as was exemplified by the preparation of compounds 2a and 2b.

Characterization of reactions of fullerene C60 with bromine. Crystal structures of bromofullerenes C60Br6, C60Br6·CS2, C60Br8·CHBr3·2Br2, and C60Br24· C6H4Cl2·Br2

Abstract: Results of research on bromination of [60]fullerene in organic solvents and liquid bromine are summarized. The conditions of the synthesis of bromofullerenes C60Br6 and C60Br8 were optimized. The formation of bromide C60Br14 was detected. A model was proposed for the description of the processes involved in bromination of C60 in organic solvents. The crystal and molecular structures of C60Br6, C60Br6·CS2, C60Br8·CHBr3·2Br2, and C60Br24·C6H4Cl2·Br2 were established by X-ray diffraction analysis.

Synthesis and structures of pyridoannelated 1,2,3,4-tetrazine 1,3-dioxides

Abstract: Treatment of 2- and 4-amino-3-(tert-butyl-NNO-azoxy)pyridines with nitrating agents (N2O5or NO2BF4) afforded the first representatives of pyridoannelated 1,2,3,4-tetrazine di-N-oxides, viz, pyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (9), 7-nitropyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (10), and pyrido[3,4-e][1,2,3,4]tetrazine 2,4-dioxide (11) These compounds were studied by 1H, 13C, and 14N NMR spectroscopy The 1:1 complex of compound 10 with benzene was studied by X-ray diffraction analysis

High pressure and supramolecular systems

Abstract: The present review summarizes the results of studies of supramolecular systems under high hydrostatic pressure. The possibilities of using high pressure for the preparation of new supramolecular structures, investigation of intermolecular interactions in these structures, and control over the physical and chemical properties of supramolecular assemblies are considered.