Synthesis and structure of cobalt complexes [Me3EtN] 2+ [CoI4]2? and [Me3BuN] 2+ [CoI4]2?

Complexes [Me₃EtN]₂⁺[CoI₄]²⁻ (I) and [Me₃EtN]₂⁺[CoI₄]²⁻ (II) were synthesized by reacting trimethylalkylammonium iodide with cobalt(II) iodide in acetone. According to X-ray diffraction data, complexes I and II consist of tetrahedral tetraalkylammonium cations (for I, N-C is 1.481(5)–1.590(8) CNC is 107.3(3)°–111.6(3)°; for II, N-C is 1.485(8)–1.506(10) ? and CNC is 106.9(7)°–111.7(5)°) and [CoI₄]²⁻ anions (for I, Co-I is 2.5951(5)–2.6127(5) ? and ICoI is 104.67(2)°–113.23(2)°; for II, Co-I is 2.5914(8)–2.5943(9) ? and ICoI is 107.05(2)°–114.42(5)°).     

trans-dinitro- and trans-dinitratoruthenium complexes [RuNO(NH3)2(NO2)2(OH)] and [RuNO(NH3)2(H2O)(NO3)2]NO3·H2O

Methods for the synthesis of trans-diammino complexes [RuNO(NH₃)₂(NO₂)₂(OH)] (I) and [RuNO(NH₃)₂(H₂O)(NO₃)₂](NO₃)·H₂O (II) are suggested. The compounds were studied by IR spectroscopy and X-ray phase and X-ray structural analyses. Crystal data: space group P-1; a = 6.2328(2) ?, b = 11.0488(3) ?, c = 11.0981(4) ?, α = 71.942(1)°, β = 83.291(1)°, γ = 86.877(1)° (I); space group P2₁; a = 6.6290(2) ?, b = 13.4389(5) ?, c = 7.0180(2) ?, β 114.281(1)° (II). Complex II readily lost some part of crystal water on storage in open air. Original Russian Text Copyright ? 2009 by M. A. Il’in, E. V. Kabin, V. A. Emel’yanov, I. A. Baidina, and V. A. Vorob’yov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 341–348, March–April, 2009.     

Laser photolysis of 1-(4-nitrophenyl)-3-methylpyrazole and 1-ethyl-3-(4-nitrophenyl)-5-chloropyrazole

The spectral kinetic characteristics of the triplet states of 1-(4-nitrophenyl)-3-methylpyrazole (1) and 1-ethyl-3-(4-nitrophenyl)-5-chloropyrazole (2) were studied by the laser nanosecond photolysis technique in different solvents. The triplet lifetimes (τ_T) of molecules 1 and 2 were found to depend strongly on the solvent nature. An increase in τ_T by approximately two orders of magnitude on going from nonpolar and polar aprotic solvents (τ_T ≤ 15 ns) to aqueous-acetonitrile solutions (τ_T = 1100 ns for a volume acetonitrile to water ratio of 1 : 3) was analyzed, taking into account the influence of the medium on the relative contribution of the n,π*- and π,π*-configurations to the lowest triplet state. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1115–1119, May, 2005.     

Synthesis and structure of gold and copper complexes: [Ph3PhCH2P]+[AuCl4]?, [NH(C2H4OH)3]+[AuCl4]? · H2O, and [Ph3EtP] 2+ [Cu2Cl6]2?

Triphenylbenzylphosphonium tetrachloroaurate (I) and triethanolammonium tetrachloroaurate hydrate (II) were prepared by reacting tetrachloroauric acid in acetone with triphenylbenzylphosphonium and triethanolammonium, respectively. Triphenylethylphosphonium hexachlorodicuprate (III) was synthesized from triphenylethylphosphonium chloride and copper chloride in acetone. The crystal structures of complexes I to III were determined by single-crystal X-ray diffraction. The phosphorus atoms in complex I have a nearly undistorted tetrahedral coordination (CPC, 108.3°–110.6°; P-C, 1.788–1.793 ?). The coordination of nitrogen atoms in the cations of complex II is a distorted tetrahedron (CNC, 111.7°–112.4°). The square coordination of aurum in I and II is only slightly distorted: the ClAuCl angles are 89.6°–90.3° (I) and 89.5°–90.6° (II) and the Au-Cl distances are 2.256–2.278 ? I) and 2.280–2.285 ? (II). The phosphorus atoms in complex III are tetracoordinated (CPC, 106.34°–111.73°; P-C, 1.790–1.795 ?). The copper atoms in III have a distorted tetrahedral coordination (ClCuCl, 98.48°–144.85°; Cu-Cl, 2.1999–2.3263 ?). The central fragment Cu₂Cl₂ in the anion of complex III is bent relative to the Cu₂ axis (the chlorine atom deviates from the Cu₂Cl plane by 0.27 ?).     

Synthesis and structure of cobalt complexes [Ph3(n-Pr)P 2+ [CoI4]2? and [Ph3(n-Am)P 2+ [CoI4]2?

Complexes Ph₃(n-Pr)P₂⁺[CoI₄]²⁻ (I) and [Ph₃(n-Am)P]₂⁺ [CoI₄]²⁻ (II) were synthesized by reactions of triphenyl(alkyl)phosphonium iodide with cobalt(II) iodide in acetone. According to the X-ray diffraction data, complexes I and II consist of tetrahedral triphenyl(alkyl)phosphonium cations (for I, P-C is 1.787(4)–1.804(4) ? and CPC is 106.73(18)°–111.4(18)°; for II P-C is 1.786(6)–1.802(6) ? and CPC is 107.6(3)°–111.7(3)°) and [CoI₄]²⁻ anions (Co-I 2.5923(6)–2.6189(6) ?, ICoI 101.86(2)°–113.25(2)° for I; Co-I 2.5899(9)–2.6171(9) 107.01(3)°–110.47(3)° for II).     

The crystal polymorphs of metazachlor

Five crystal polymorphs of the herbicide metazachlor (MTZC) were characterized by means of hot stage microscopy, differential scanning calorimetry, IR- and Raman spectroscopy as well as X-ray powder diffractometry. Modification (mod.) I, II and III° can be crystallized from solvents and the melt, respectively, whereas the unstable mod. IV and V crystallize exclusively from the super-cooled melt. Based on the results of thermal analysis and solvent mediated transformation studies, the thermodynamic relationships among the polymorphic phases of metazachlor were evaluated and displayed in a semi-schematic energy/temperature-diagram. At room temperature, mod. III° (T _fus =76°C, Δ_fus H _III =26.6 kJ mol^-1) is the thermodynamically stable form, followed by mod. II (T _fus =80°C, Δ_fus H _II =23.0 kJ mol^-1) and mod. I (T _fus =83°C, Δ_fus H _II=19.7 kJ mol^-1). These forms are enantiotropically related showing thermodynamic transition points at ~55°C (T _{trs, III/II}), ~60°C (T _{trs, III/I}) and ~63°C (T _{trs, II/I}). Thus mod. I is the thermodynamically stable form above 63°C, mod. III° below 55°C and mod. II in a small window between these temperatures. Mod. IV (T _fus =72-74°C, Δ_fus H _II =18.7 kJ mol^-1) and mod. V (T _fus =65°C) are monotropically related to each other as well as to all other forms. The metastable mod. I and II show a high kinetic stability. They crystallize from solvents, and thus these forms can be present in commercial samples. Since metazachlor is used as an aqueous suspension, the use of the metastable forms is not advisable because of a potential transformation to mod. III°. This may result in problematic formulations, due to caking and aggregation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Catalytic activity of H-ZSM-5 and H-ZSM-5/AL-MCM-41 in the conversion of ethanol to gasoline fraction hydrocarbons

H-ZSM-5 (Si/Al = 10.6 and 20) efficiently catalyzes the transformation of ethanol into C₅-C₁₂ gasoline hydrocarbons in 27–33 mass % yield at 320°C and feed rate 20 mmol C₂H₅OH/(gcat·h). Only ethylene is produced on the mesoporous zeolite H-ZSM-5/Al-MCM-41 with 100% ethanol conversion. This discrepancy may be attributed to blockage of the ZSM-5 micropores in the mesoporous zeolite structure.     

New π ligand N,N,N,N′,N′,N′-hexaallylethylenediaminium (L2+): Synthesis and crystal structures of LBr2 · 2H2O and its cuprocomplexes L[CuII(Br0.45Cl3.55)], L[Cu 4I (Br4.55Cl1.45)], and L[Cu 4I Br6]

The alkylation of ethylenediamine with allyl bromide in the presence of a fourfold (with respect to ethylenediamine) molar amount of NaHCO₃ in acetone with an ethanol admixture (15: 1) affords LBr₂ · 2H₂O (I), where L²⁺ is the N,N,N,N′,N′,N′-hexaallylethylenediaminium cation. Single crystals of complexes L[Cu^II(Br_0.45Cl_3.55)] (II), L[Cu₄^I(Br_4.55Cl_1.45)] (III), and L[Cu₄^IBr₆] (IV) are prepared by ac electrochemical synthesis from an ethanolic solution of LBr₂ · 2H₂O, CuCl₂ · 2H₂O (or CuBr₂) at copper wire electrodes. The crystal structures of compounds I–IV are determined by X-ray diffraction analysis. The crystals of complex I are monoclinic: space group P2₁/n, a = 8.544(3), b = 10.404(3), c = 13.350(4) ?, β = 97.29(3)°, V = 1177.2(6) ?³, Z = 2. The bromine anions in compound I are bonded to the L²⁺ cations and water molecules through hydrogen contacts (E)H…Br (E = O, C) of 2.57(3)–2.86(3) ?. The crystals of compounds II–IV are triclinic: space group P . For II: a = 8.762(4), b = 9.163(4), c = 16.500(6) ?, α = 95.62(4)°, β = 96.39(4)°, γ = 111.46(4)°, V = 1211.4(9) ?³, Z = 2; for III: a = 9.074(4), b = 9.435(4), c = 9.829(5) ?, α = 116.12(4)°, β = 104.14(4)°, γ = 100.22(4)°, V = 692.3(6) ?³, Z = 1; for IV isostructural III: a = 9.084(4), b = 9.404(4), c = 9.869(4) ?, α = 116.31(3)°, β = 104.00(3)°, γ = 100.37(3)°, V = 692.1(5) ?³, Z = 1. Unlike the isolated tetrahedral CuX₄²⁻ anion in structure II, an original chain anion (Cu₄X₆²⁻) _n is observed in the structures of π complexes III and IV. Original Russian Text ? M.M. Monchak, A.V. Pavlyuk, V.V. Kinzhibalo, M.G. Mys’kiv, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 414–419.     

Gas phase nitration of benzene by nitric acid on ZSM-5 zeolite

Gas phase nitration of benzene on ZSM-5 zeolite has been studied at 140–170°C. Increase in the HNO₃/C₆H₆ ratio of the starting mixture was shown to increase the nitrobenzene yield. Process parameters worsened with time since reagents and products were strongly adsorbed and left the zeolite surface only at 220–250°C as CO, CO₂ and NO.     

New oxadiazole derivatives as promising electron transport materials: synthesis and characterization of thermal, optical and electrochemical properties

2,5-bis-(4-biphenyl)-yl-1,3,4-oxadiazole (1a), 2,5-bis-(4-(6,8-difluoro)-biphenyl)-yl-1,3,4-oxadiazole (1b) and 2,5-bis-(4-(spiro-fluorenyl)-phenyl)-yl-1,3,4-oxadiazole (1c) were designed, synthesized and characterized. 1a–c were easily obtained from Suzuki reactions between 2,5-bis-(4-bromo-phynyl)-[1,3,4]oxadiazole (2) and aromatic boronic acids (3). They were characterized by ¹H-NMR, DSC, TGA, UV-Vis, photoluminescence (PL) spectrometry and CV. The melting temperatures (T _m ) of 1a–c are 237, 208 and 370 °C, respectively, much higher than that of 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD, T _m = 136 °C). The oxidation potentials of 1a–c are 1.86, 1.94 and 1.18 V, and their reduction potentials are −2.31, −2.22 and −2.27 V, respectively, indicating that the introduction of electronegative oxadiazole unit lowers the electron density in molecules and enhances their stabilities. The LUMO/HOMO energy levels of 1a–c are as low as −2.39/−6.56, −2.48/−6.69 and −2.43/−5.88 eV, respectively. The good thermal stabilities and low orbital levels of 1a–c make them promising electron-transporting or hole-blocking materials for organic optoelectronic devices.     

Dimethyl disulfide conversion into dimethyl sulfide in the presence of sulfidized catalysts

The conversion of dimethyl disulfide in the presence of various supported sulfidized metal-containing catalysts at atmospheric pressure and T = 150−350°C was studied. Sulfidized transition metals supported onto aluminum oxide were more active than catalysts based on a carbon support, silicon dioxide, amorphous aluminosilicate, and zeolite ZSM-5. The most active catalyst was 10% Co/Al₂O₃ prepared with the use of cobalt acetate as an active component precursor and treated with a mixture of hydrogen sulfide with hydrogen at T = 400°C. From kinetic data, it follows that all of the reaction products were formed simultaneously at a temperature of <200°C, whereas a consecutive reaction scheme took place at higher temperatures. In the presence of a sulfidized alumina-cobalt catalyst, the output of dimethyl sulfide was higher than that reached with the use of other well-known catalysts.     

Protolytic properties and complexation with copper(II) ions of some azo derivatives of β-arylaminopropionic acids

The azo coupling reaction of N-(2-carboxyethyl)anthranilic acid and N,N,N′,N′-tetrabis(2-carboxyethyl)-1,3-phenylenediamine with diazosulfanilic acid yielded the complexones sodium 4-N-(2-carboxyethyl)amino-5-carboxyazobenzene-4′-sulfonate (I) and 2,4-N,N,N′,N′-tetrabis(2-carboxyethyl)diaminoazobenzene-4′-sulfonic acid (II), respectively. The acidity constants of I and II (20°C, μ = 0.1M KCl) were determined to be as follows: for I, pK ₀₀ = 1.29 ± 0.13, pK ₀ = 2.92 ± 0.07, pK ₁ = 3.92 ± 0.05, pK ₂ = 5.16 ± 0.03; for II, pK ₀₀ = 2.35 ± 0.06, pK ₀ = 2.81 ± 0.09, pK ₁ = 3.21 ± 0.11, pK ₂ = 3.81 ± 0.09, pK ₃ = 4.34 ± 0.04, pK ₄ = 5.03 ± 0.06, pK ₅ = 6.67 ± 0.07. The electronic absorption spectra of I and II were measured, and acid-base equilibrium scheme for I and II in aqueous solutions were suggested. The complexation constants of I and II with copper(II) ions were determined to be logK _CuQ^I= 5.47 ± 0.06 and logK _CuQ^II= 5.72 ± 0.13 (20°C, μ = 0.1 M KCl).     

Synthesis and vibrational spectra of copper(II) and erbium(III) complexes with 2-[2′-(oxymethyldiphenylphosphinyl)phenyldiazenyl]-4- tert -butylphenol (HL) [CuL2] · 2H2O and Er(NO3)2 · 2 HL · 2H2O. Crystal structure of [CuL2] · 2H2O

The syntheses of the complex copper salt CuL₂ · 2H₂O (I) and the erbium nitrate complex Er(NO₃)₃ · 2HL · 2H₂O (II) (HL is 2-[2′-(oxymethyldiphenylphosphinyl)phenyldiazenyl]-4-tert-butylphenol) have been described. Basic vibrational frequencies in the IR spectra of I and II have been interpreted. The crystal structure of I has been determined by X-ray crystallography: the crystals are monoclinic, a = 15.157(3) ?, b = 17.080(2) ?, c = 22.451(9) ?, β = 106.09(3)°, V = 5584(3) ?³, Z = 4, space group C2/c, R = 0.0546 (for 1152 reflections with I > 2σ(I)). The coordination polyhedron of the copper atom (symmetry C ₂) can be described as a symmetrically elongated square bipyramid (4+2). The basic square of the Cu polyhedron is formed by the oxygen atom of the substituted phenol and one of the nitrogen atoms of the azo group of each of the two deprotonated ligands L⁻ (Cu-N, 1.969(6) ?; Cu-O, 1.899(5) ?). The angles between the opposite O and N atoms are 157.6°, and the other equatorial angles are in the range 90.6°–95.9°. The axial positions are occupied by the anisole O(2) and O(2A) atoms (Cu-O, 2.737(6) ?, the O(2)Cu(1)O(2A) angle, 132.3°). In the crystal of I, complex molecules and water molecules of crystallization are combined by a system of hydrogen bonds. IR spectra show that, in complex II, as distinct from compound I, the HL ligand is coordinated to the erbium atom through the phosphoryl oxygen atom. Original Russian Text ? A.Yu. Tsivadze, L.Kh. Minacheva, I.S. Ivanova, V.E. Baulin, E.N. Pyatova, V.S. Sergienko, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 4, pp. 601–607.     

Electrochemical study of the thionine dye incorporated into ZSM-5 and HZSM-5 zeolites

The electrochemical properties of thionine dye adsorbed into ZSM-5 and HZSM-5 zeolites (TH/ZSM-5, TH/HZSM-5) are studied in 0.5 M KCl solution. The dye is strongly retained and not easily leached from the zeolites matrix. The samples are incorporated into the carbon paste electrode (TH/ZSM-5/P, TH/HZSM-5/P) for cyclic voltammetric measurements. The redox reactions of thionine incorporated into ZSM-5 zeolite contain a quasi-reversible, two-electron one proton in the pH range 1 to 10, but thionine-loaded HZSM-5 zeolite undergoes a quasi-reversible two-electron two-protons redox reaction under acidic conditions and a one proton two-electron redox reaction takes place under basic conditions. The separation of the anodic and cathodic potentials (E _p) is high in thionine-loaded zeolites (>100) with respect to the solution of thionine (E _p = 34 for ZSM-5/P and 36 mV for HZSM-5/P), indicating that there are strong interaction between thionine molecules and the zeolites. The midpoint potentials (E _m) for TH/ZSM-5/P and TH/HZSM-5/P are −0.203 and −0.381 V, respectively. However, the midpoint potentials for the solution of thionine for the electrode system of ZSM-5/P and HZSM-5/P are −0.335 and −0.407 V, respectively. Thus, thionine dye molecules incorporated into the zeolites can be reduced more easily with respect to solution of thionine. In various electrolyte solutions, the midpoint potentials remains constant, but the midpoint potential of the thionine-zeolite electrodes depends on the solution pH. Influence of the pH of the solution on the midpoint potential of an immobilized dye reveals that thionine molecules are accessible to protons. This property is ascribed to the formation of mesopores in the structure of our zeolites suffering from a calcination step. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 7, pp. 794–800. The text was submitted by the authors in English     

Measuring the ignition delay time for hydrogen-oxygen mixtures behind the front of an incident shock wave

The delay time τ has been measured for the formation of the ^·OH radical in igniting hydrogenoxygen mixtures diluted with argon (79–97%). The experiments have been carried out under incident shock wave conditions at temperatures of 900–3000 K, pressures of 0.5–2.5 atm, and H₂/O₂ ratios of 0.2–20. The dependence of τ on the pressure P _s of the stoichiometric part of the combustible mixture (2H₂-O₂) has been investigated for different mixture compositions. Under the above conditions, τ depends practically linearly on 1/P _s at P _s = 0.02−0.1 atm, irrespective of the mixture composition. This allows the measured τ data to be converted to one quantity, τP _s. The temperature dependence of τP _s in the P _s range from 0.02 to 0.1 atm is Arrhenius-like. For the hydrogen-rich mixtures (H₂/O₂ = 2–20), this dependence appears as τP _s= 0.057 + 0.0256exp(7470/T) μs atm; for the lean mixtures (H₂/O₂ = 0.125–1), τP _s = 0.021 + 0.0069exp(7470/T) μs atm. The length of the shock-heated gas plug in the incident shock wave poses limitations on the ignition delay time measurements at T < 900 K.     

Syntheses and properties of poly (amide–imide)s based on 5,5′-bis[4-(4-trimellitimidophenoxy)phenyl]-hexahydro-4,7-methanoindan and aromatic diamines

 A novel polymer-forming diimide–diacid, 5,5′-bis[4-(4-trimellitimido phenoxy)phenyl]-hexahydro-4,7-methanoindan (II), was prepared by the condensation reaction of 5,5′-bis[4-(4-aminophenoxy)phenyl]-hexahydro-4,7-methanoindan with trimellitic anhydride. A series of novel aromatic poly(amide–imide)s (PAIs) containing polycyclic cardo groups was prepared by the direct polycondensation of II with various aromatic diamines using phosphorylation techniques. The polymers had inherent viscosities between 0.71 and 0.96 dl/g. The polymers were soluble in polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide, and could be cast from their DMAc solutions into transparent, flexible, and tough films, except for III _a . These films had yield strengths of 85–114 MPa, tensile strengths of 77–102 MPa, an elongation at break of 8–17%, and initial moduli of 2.0–2.7 GPa. Wide-angle X-ray diffraction revealed that the polymers are amorphous. The glass-transition temperatures of the polymers were in the range 242–312 °C. All the PAIs exhibited no appreciable decomposition below 430 °C, and their 10%-weight-loss temperatures were in the range 484–507 °C in nitrogen and 494–515 °C in air. Received: 26 January 1999 Accepted in revised form: 11 May 1999     

Crystal and molecular structure and properties of [Ni(4-NH2Py)2(iso-Bu2PS2)2] and [Co(4-NH2Py)(iso-Bu2PS2)2]

The interaction of the Co(iso-Bu₂PS₂)₂ chelate with 4-NH₂Py afforded a paramagnetic complex [Co(4-NH₂Py)(iso-Bu₂PS₂)₂] (μ_eff = 4.53 BM). Single crystals of [Ni(4-NH₂Py)₂(iso-Bu₂PS₂)₂] (I) and [Co(4-NH₂Py)(iso-Bu₂PS₂)₂] (II) were grown and used for X-ray diffraction investigation (X8 APEX diffractometer, MoK _α radiation). Crystals I are monoclinic with unit cell parameters a = 12.5336(5) Å, b = 9.4356(4) Å, c = 16.4095(6) Å; β = 111.351(1)°; V = 1807.4(1) ų; Z = 2, ρ = 1.223 g/cm³, space group P2₁/n. Crystals II are triclinic with unit cell parameters a = 8.7572(4) Å, b = 9.6934(6) Å, c = 18.665(1) Å; α = 79.374(2)°, β = 87.049(2)°, γ = 75.640(2)°; V = 1508.6(1) ų; Z = 2, ρ = 1.259 g/cm³; space group . The structures of I and II are formed by isolated mononuclear molecules. The coordination unit is NiN₂S₄ (octahedron) in I and CoNS₄ (tetragonal pyramid) in II. The 4-NH₂Py molecule is coordinated through the N atom of the heterocycle. Electronic spectroscopy data for II agree with the symmetry of the NS₄ polyhedron found by X-ray diffraction (XRD) analysis. The noncoordinated amine groups link the complex molecules via N-H...S hydrogen bonds. __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 6, pp.1072–1080, November–December, 2005. Original Russian Text Copyright ? 2005 by T. E. Kokina, L. A. Glinskaya, E. A. Sankova, R. F. Klevtsova, and S. V. Larionov     

Crystal structure of cadmium iodide complexes with acetamide and propaneamide [Cd(CH3CONH2)6][Cd2I6] and [Cd(C2H5CONH2)6][Cd2I6]

The complexes of CdI₂ with acetamide (AA) and propaneamide (PrA) of the composition [Cd(AA)₆][Cd₂I₆] (I) and [Cd(PrA)₆][Cd₂I₆] (II) were synthesized and studied by X-ray diffraction. Isostructural crystals I and II are triclinic: a = 7.285(3) and 8.066(6), b = 11.266(4) and 11.649(3), c = 11.554(3) and 12.063(2) ?, α = 100.96(2)° and 102.74(2)°, β = 91.59(2)° and 91.73(4)°, γ = 100.76(3)° and 101.05(4)°, V = 912.5 and 1081.9 ?³, respectively; space group , Z = 1. Original Russian Text ? I.A. Zamilatskov, E.V. Savinkina, D.V. Al’bov, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 6, pp. 407–410.     

Mixed-ligand complex compounds [Pb(Phen)×{(iso-C4H9)2PS2}2] and [Pb(2,2′-Bipy){(iso-C4H9)2PS2}2] and formation of supramolecular assemblies in their crystal structures

Mixed-ligand complex compounds [Pb(Phen)(i-Bu₂PS₂)]₂ (I) and [Pb(2,2′-Bipy)(i-Bu₂PS₂)]₂ (II) were synthesized. Their structures were determined from X-ray diffraction data (X8 APEX diffractometer, MoK _α radiation, 6392 _Fhkl , R = 0.0233 for I and 3937 F _hkl , R = 0.0252 for II). Crystals I are triclinic: a = 10.2662(3) Å, b = 12.3037(2) Å, c = 14.8444(4) Å; α = 92.054(1)°, β = 103.473(1)°, γ = 105.561(1)°, V = 1746.89(8) ų, Z = 2, ρ_calc = 1.532 g/cm³, space group P . Crystals II are monoclinic: a = 9.3462(3) Å, b = 26.3310(12) Å, c = 28.5345(13) Å; β = 96.436(1)°, V = 6977.9(5) ų, Z = 8, ρ_calc = 1.489 g/cm³, space group P2₁/n. The structures are built from mononuclear molecules. In both structures, the intermolecular contacts between the Pb and S atoms of the neighboring mononuclear molecules form supramolecular assemblies involving two molecules. The environment of the Pb atoms in the assemblies is a pentagonal bipyramid, N₂S₄₊₁. The assemblies are joined into ribbons by π-π interactions of the Phen rings in I and C…C short contacts between the pyridine rings in II. Original Russian Text Copyright ? 2008 by R. F. Klevtsova, E. A. Sankova, T. E. Kokina, L. A. Glinskaya, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 1, pp. 123–131, January–February, 2008.     

Preparation and characterization of transparent TiO2 thin films coated on fused-silica substrates

The transparent TiO₂ thin films coated on fused-SiO₂ substrates were prepared by the sol–gel method and spin-coating technique. Effects of calcination temperature on crystal structure, grain size, surface texture, and light transmittance of the films were investigated. After calcining at 600–1,200 °C, the thicknesses of the TiO₂ films were all around 80 nm and the molecular structures of the films were anatase, even at 1,200 °C. The calcined TiO₂ films had the ultraviolet light (wavelength 200–400 nm) transmittances of ≤29% and the visible light (wavelength 400–800 nm) transmittance of ≥72%. By photocatalytically decomposing the methylene blue (MB) in water, the photocatalytic activities of the TiO₂ thin films were measured and represented using the characteristic time constant (τ) for the MB degradation. While the films prepared at 1,000 and 1,200 °C photodecomposed about 54 mol% of the MB in water (the corresponding τ ≈ 14.8 h) after exposing to 365-nm UV light for 12 h, the films prepared at 600 and 800 °C had smaller τ (≈9.0 h) and photodecomposed about 74 mol% of the MB in water at the same testing conditions.