Mixed ligand palladium(II) and platinum(II) complexes of tertiary diphosphines and benz-1,3-imidazoline-2-thione,benz-1,3-oxazoline-2-thione or benz-1,3-thiazoline-2-thione

Palladium(II) and platinum(II) complexes containing the mixed ligands tertiary diphosphines Ph₂P(CH₂) _n PPh₂, (n = 1–4) and benz-1,3-imidazoline-2-thione, benz-1,3-oxazoline-2-thione or benz-1,3-thiazoline-2-thione have been prepared and characterized by elemental analysis, magnetic susceptibility, molar conductance and i.r. spectral data. ³¹P–{¹H}-n.m.r. data have been applied to characterize the produced linkage isomers.     

Convenient synthesis of dodeca-1,3-diynyl ketones by the “diacetylene zipper” reaction

Dodeca-1,3-diynyl ketones were synthesized by isomerization of dodeca-5,7-diyne with H₂N(CH₂)₂NHLi and treatment of the in situ prepared lithium derivative of dodeca-1,3-diyne with N-methoxy-N-methylcarboxamides. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1017–1019, April, 2005.     

Catalytic transformations of oligocarbosilanes induced by AlCl3

Catalytic activation of Si−C bonds in poly(vinyltrimethylsilane) was studied using a model reaction of catalytic transformations of oligocarbosilanes Me₃Si(CH₂) _n SiMe₃ (n=2, 3) in dichlorodimethylsilane in the presence of AlCl₃ as an example. The formation of ClMe₂Si(CH₂) _n SiMe₃ was established by chromato-mass spectrometry and GLC. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2265–2266, December, 1997.     

Phenyl(acyloxy)fluorosilanes C6H5Si(OCOR)nF3?n (n = 1, 2) and phenyl(acyloxy)fluorochlorosilanes C6H5Si(OCOR)FCl

The method of synthesis of the hitherto unknown class of organosilicon compounds, phenyl(acyloxy)fluorosilanes C₆H₅Si(OCOR) _n F_3−n (n = 1, 2) and phenyl(acyloxy)fluorochlorosilanes C₆H₅Si(OCOR) FCl in up to 91% yield has been developed based on the reaction of phenyl(fluoro)chlorosilanes C₆H₅SiCl _n F_3−n (n = 1, 2) with trimethylsilyl esters of carboxylic acids Me₃SiOC(O)R [R = H, CH₃, CF₃, CCl₃, ClCH₂, BrCH₂, CH₂=CHCH₃, CH₂=CHPh, CH(CH₃)=CH₂, Ph].     

New route to 1,1-difluoro-5-methylquasisilatrane

A new route to 1,1-difluoro-5-methylquasisilatrane (N→Si) F₂Si(OCH₂CH₂)₂NMe is elaborated: the reaction of chlorinated methyltrifluorosilanes F₃SiCH_3−n Cln (n = 1–3) as well as trifluoro(3-chloropropyl) silane and trifluoro(propenyl)silane with N-methyl-bis(2-hydroxyethyl)amine. The reactivity of the silanes F₃SiCH_3−n Cl _n increases with the number of chlorine atoms, that is, with the electronegativity of the CH_3−n Cl _n group.     

Crystal Structure and Conformation of a 10-Thiabilirubin

 A crystal structure determination of a bilirubin analog with a sulfur instead of a C(10)–CH₂ linking the two dipyrrinones is reported. Conformation-determining torsion angles and key hydrogen bond distances and angles are compared to those obtained from molecular dynamics calculations as well as to the corresponding data from X-ray determinations and molecular dynamics calculations of bilirubin. Like other bilirubins, the component dipyrrinones of the analog are present in the bis-lactam form with (Z)-configurated double bonds at C(4) and C(15). Despite the large differences in bond lengths and angles at –S–vs.–CH₂–, the crystal structure shows considerable similarity to bilirubin: both pigments adopt a folded, intramolecularly hydrogen-bonded ridge-tile conformation stabilized by six hydrogen bonds – although the interplanar angle of the ridge-tile conformation of the title compound is smaller (∼ 86°) than that of bilirubin (∼ 98°). The collective data indicate that even with long C–S bond lengths and a smaller C–S–C bond angle at the pivot point on the ridge-tile seam, intramolecular hydrogen bonding persists.     

O-Tolyl/benzyl dithiocarbonates of phosphorus(III) and (V): syntheses and characterization

Abstract  

O-Tolyl/benzyl dithiocarbonates, ROCS₂Na (R = o-, m-, or p-CH₃C₆H₄–, and –CH₂C₆H₅), were synthesized and characterized. These new ligands reacted with PCl₃/POCl₃ in refluxing toluene which resulted in the formation of phosphorus(III) and phosphorus(V) tolyl/benzyl dithiocarbonates corresponding to [(ROCS₂) _n PCl_3−n ] and [(ROCS₂) _n POCl_3−n ] (R = o-, m-, or p-CH₃C₆H₄–, and –CH₂C₆H₅; n = 1, 2, 3). These pale yellow liquid compounds were characterized by IR, mass, and NMR (¹H, ¹³C, and ³¹P) spectral studies, which suggest the dithiocarbonate ligands bind in a monodentate mode leading to P–S–C linkages in these derivatives.     

Carbofunctional fluorine-containing triethoxysilanes: synthesis,film forming and properties

Novel fluorine-containing carbofunctional organosilicon monomers were synthesized: 3-pentafluorobenzylideneaminopropylethoxysilane (EtO)₃Si(CH₂)₃N=CH-C₆F₅, N-3-methoxydiethoxysilylpropyltrifluoroacetamide (EtO)₂(MeO)Si(CH₂)₃NHC(O)CF₃, and 1,1,5-trihydrooctafluoroamyl N-3-triethoxysilylpropylaminopropanoate (EtO)₃Si(CH₂)₃NH(CH₂)₂C(O)OCH₂(CF₂)₃CHF₂. Compositions for the formation of transparent thermally stable films were prepared from these monomers. The films have low absorbance intensity near 1550 nm, i.e., in the region of photosignal transmission of modern optical communication systems. The compositions can dissolve complexes with organofluorine ligands and produce transparent homogeneous films doped with rare-earth metals. The concentrations of the complexes in the matrices are 3.7–21.4 wt.% (metal concentrations are 0.6–3.7%). Fluorescence and fluorescence excitation spectra of the matrices and electronic absorption spectra of the doped films were studied. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1131–1138, May, 2005.     

Changes in the conformational parameters of 1-allylbenzotriazole in a mixed halide π-complex [CuCl0.85Br0.15(C6H4N3CH2=CH2)] under the action of bromine atoms

Single crystals of [CuCl_0.85Br_0.15(C₆H₄N₃CH₂=CH₂)] (I) were obtained by alternating current electrochemical synthesis; their X-ray structural investigation has been carried out (DARCh automatic diffractometer, MoK _α radiation, θ/2θ scanning; 1460 reflections with F ≥ 4σ(F), R = 0.0517). The crystals are monoclinic, their space group is P2₁/c, a = 7.292(3) Å, b = 17.947(8) Å, c = 7.398(4) Å, β = 93.56(4)°, V = 966(1) ų, Z = 4). Complex I is close in structure to the previously investigated compound [CuCl(C₆H₄N₃CH₂=CH₂)] (II). In both structures, the trigonal-pyramidal surroundings of the copper atom include two halide atoms (one is apical), a nitrogen atom, and a C=C group. The Cu₂X₂ dimers are associated into {[Cu₂X₂(C₆H₅N₃CH₂=CH₂)]}_n layers due to the bridging function of the 1-allylbenzotriazole molecule. In spite of the similar coordination polyhedra of the metal atoms and identical bridging function of the ligand molecule in I and II, the differences in the conformation parameters of the allyl group π-coordinated by the copper(I) atom (trans-like in I and cis-like in II) caused by the presence of bromine atoms in the coordination sphere predetermine different structures of the organometallic [Cu₂X₂(C₆H₅N₃CH₂=CH₂)]₄ tetramer subunits in the layers and, as a consequence, formation of different crystal structures. Original Russian Text Copyright ? 2005 by E. A. Goreshnik, B. M. Mykhalichko, and V. N. Davydov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 1, pp. 174–178, January–February, 2005.     

Synthesis and Structural Characterization of a New Macrocyclic Polysiloxane-immobilized Ligand System

Summary. A new porous solid macrocyclic 1,4,7,11,14-pentaazapentadecane-3,15-dione polysiloxane ligand system of the general formula P–(CH₂)₃–C₁₁H₂₂O₂N₅ (where P represents [Si–O]_n siloxane network) has been prepared by the reaction of polysiloxane-immobilized iminobis(N-(2-aminoethyl)acetamide) with 1,3-dibromopropane. The FTIR and XPS results confirm the introduction of the macrocyclic functional ligand group into the polysiloxane network. The new macrocyclic polysiloxane ligand system exhibits high potential for the uptake of metal ions (Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺).     

Synthesis and Structural Characterization of a New Macrocyclic Polysiloxane-immobilized Ligand System

A new porous solid macrocyclic 1,4,7,11,14-pentaazapentadecane-3,15-dione polysiloxane ligand system of the general formula P–(CH₂)₃–C₁₁H₂₂O₂N₅ (where P represents [Si–O]_n siloxane network) has been prepared by the reaction of polysiloxane-immobilized iminobis(N-(2-aminoethyl)acetamide) with 1,3-dibromopropane. The FTIR and XPS results confirm the introduction of the macrocyclic functional ligand group into the polysiloxane network. The new macrocyclic polysiloxane ligand system exhibits high potential for the uptake of metal ions (Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺).     

Metal Oxoclusters as Molecular Building Blocks for the Development of Nanostructured Inorganic–Organic Hybrid Thin Films

Summary. Silica-based inorganic–organic hybrid thin films embedding the organically modified oxohafnium clusters (Hf₄O₂(OMc)₁₂, OMc=OC(O)–C(CH₃)=CH₂) were obtained by photo-activated free radical copolymerisation of the methacrylate groups of the cluster with those of the pre-hydrolysed (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH₂=C(CH₃)C(O)O)(CH₂)₃Si(OCH₃)₃). By this route, a covalent anchoring of the cluster to the forming silica network was achieved. Samples characterized by two different Si/Hf compositions (18:1, 5:1) were prepared. The surface and in-depth composition of the thin films were investigated through Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). XPS depth profiles performed on the thin layers evidenced a homogenous in depth distribution of the hafnium guest species within the whole silica films and sharp film-substrate interfaces. Broad band dielectric spectroscopy (BDS) measurements permitted to investigate the electric response of the obtained films in the frequency and temperature range of 40 Hz – 1 MHz and 0–160°C.     

Metal Oxoclusters as Molecular Building Blocks for the Development of Nanostructured Inorganic–Organic Hybrid Thin Films

Silica-based inorganic–organic hybrid thin films embedding the organically modified oxohafnium clusters (Hf₄O₂(OMc)₁₂, OMc=OC(O)–C(CH₃)=CH₂) were obtained by photo-activated free radical copolymerisation of the methacrylate groups of the cluster with those of the pre-hydrolysed (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH₂=C(CH₃)C(O)O)(CH₂)₃Si(OCH₃)₃). By this route, a covalent anchoring of the cluster to the forming silica network was achieved. Samples characterized by two different Si/Hf compositions (18:1, 5:1) were prepared. The surface and in-depth composition of the thin films were investigated through Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). XPS depth profiles performed on the thin layers evidenced a homogenous in depth distribution of the hafnium guest species within the whole silica films and sharp film-substrate interfaces. Broad band dielectric spectroscopy (BDS) measurements permitted to investigate the electric response of the obtained films in the frequency and temperature range of 40 Hz – 1 MHz and 0–160°C.     

Reactions of diazoalkanes with unsaturated compounds 15. Catalytic reactions of unsaturated carbonyl compounds and their derivatives with diazomethane

The present study concerned with the influence of the nature of the acetal fragment in unsaturated compounds on the reactivity of the C=C bond in cyclopropanation reactions with diazomethane catalyzed by copper and palladium compounds. The acetal substituents at the α- or γ-position with respect to the C=C bond were found to exert an activating effect on the yields of cyclopropanation products compared to the starting unsaturated carbonyl compounds, which give 1,3-dipolar cycloaddition adducts with CH₂N₂ as by-products. Cyclopropanation of the double bonds appeared to be most efficiently catalyzed by Pd(acac)₂. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 979–983, April, 2005.     

New heterosilocanes, 1,1-difluoroand 1-phenyl-1-fluoro-2,8-dioxa-5-chalcogenosilocanes

The earlier unknown Si-fluorinated 2,8-dioxa-5-chalcogenosilocanes RFSi(OCH₂CH₂)₂Y (R = Ph, F; Y = O, S) were synthesized. According to calculations, there is a weak transannular coordinate interaction Y→Si (Y = O, S), which is much weaker than that in the isostructural quasisilatranes (Y = N). At low temperatures, 1,1-difluoro-2,5,8-trioxasilocane forms a dimer, in which two molecules of the monomer are linked by four fluorine bridges Si-F→Si located in pairs in the two orthogonal planes SiF₂Si.     

Trends in the formation of aggregates and crystals from M@Si<Subscript>16</Subscript> clusters: a study from first principle calculations

We have shown recently that the ground state and low-lying energy isomers of the endohedral M@Si₁₆ clusters (M = Sc⁻, Ti, V⁺) have a nearly spherical cage-like symmetry with a closed shell electronic structure which conforms them as exceptional stable entities. This is manifested, among other properties, by a large Homo–Lumo gap about 2 eV which suggest the possibility of using these clusters as basic units (superatoms) to construct optoelectronic materials. As a first step in that direction, we have studied in this work, by means of first principles calculations, the trends in the formation of [Ti@Si₁₆] _n , [Sc@Si₁₆K] _n , and [V@Si₁₆F] _n aggregates as their size increases, going from linear to planar to three dimensional arrangements. The most favorable configurations for n ≥ 2 are those formed from the fullerene-like D_4d isomer of M@Si₁₆, instead of the ground state Frank–Kasper T _d structure of the isolated M@Si₁₆ unit, joined by Si–Si bonds between the Si atoms of the square faces. In all cases the Homo–Lumo gap for the most favorable structure decrease with the size n. Trends for the binding energy, dipole moment, and other electronic properties are also discussed. Several crystal structures constructed from these superatom, supermolecules, and aggregates have been tested and preliminary results are summarily commented.     

不同硅铝比Cu-ZSM-5纳米片上N2O催化分解

以双季铵盐表面活性剂为模板剂,水热条件下合成了硅铝比(nSi/nAl)为18、26和95的ZSM-5沸石纳米片,采用离子交换方法制备了铜改性的ZSM-5纳米片样品,并测试了其催化分解N_2O性能。结合X射线衍射(XRD)、N_2吸附/脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)、透射电镜(TEM)、氢气程序升温还原(H_2-TPR)、氧气程序升温脱附(O_2-TPD)和原位红外漫反射光谱(CODRIFT)等表征结果 ,探讨了沸石硅铝比对于催化剂N_2O分解性能的影响及其原因。结果表明,ZSM-5纳米片硅铝比越低,CuZSM-5纳米片催化剂的活性越高。催化活性的提高归因于低硅铝比催化剂上Cu~+活性物种可还原性的增强和吸附氧脱附能力的提高。     

Layered structure of the silver coordination polymer with nonrigid aromatic diamine {Ag[CH2(C6H4NH2)2]2(CH3C6H4NH2)}NO3

The complex [Ag(DDM)₂(CH₃C₆H₄NH₂)]NO₃, where DDM is 4,4-diaminodiphenylmethane [CH₂(C₆H₄NH₂)₂], was synthesized and its structure was determined. The crystals are monoclinic, space group P2₁/n, a = 9.543(2) ?, b = 18.056(4) ?, c = 1.901(2) ?, β = 106.94(3)°, V = 1796.8(6) ?³, ρ_calcd = 1.443 g/cm³, Z = 4. The Ag atom (at the inversion center) is coordinated at the vertices of an almost undistorted octahedron by six nitrogen atoms of the primary amino groups from four bridging DDM molecules and two terminal p-toluidine molecules (Ag-N, 2.546(3) ?; NAgN, 89.7–90.3°). Wavelike layers composed of conjugate multiunit metal rings, each containing four Ag⁺ ions and four bridging DDM ligands, are formed in the structure in the [101] direction (a 2D polymer). Uncoordinated NO ₃ ⁻ anions are arranged in the cavities between the layers and link them by N-H⋯O hydrogen bonds. Original Russian Text ? Yu.V. Kokunov, V.V. Kovalev, Yu.E. Gorbunova, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 12, pp. 1992–1998.     

Cyclopropane ring opening in the reaction of methylenecyclopropane with silyl radicals stabilized on an activated Aerosil surface

Alkyl type radicals stable at room temperature and incorporating a double bond not conjugated with the free valence, ≡Si−C(=CH₂)−CH₂−CH₂, are formed in the reaction of methylenecyclopropane with silyl radicals (≡SiO)₃Si on an activated Aerosil surface. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1065–1066, May, 1997.     

Electrochemical materials science: tailoring intrinsically conducting polymers. The example: substituted thiophenes

A series of 3-(p-X-phenyl) thiophene monomers (X= –H, –CH₃, –OCH₃, –COCH₃, –COOC₂H₅, –NO₂) was electrochemically polymerized to furnish polymer films that could be reversibly reduced and oxidized (n- and p-doped). The oxidation potentials of the monomers and formal potentials of the n- and p-doping processes of polymers were correlated with resonance and inductive effects of the substituents on the phenyl ring as well as the semiempirically calculated heat of formation of the monomer radical cations. Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, March 13-16, 2005