Synthesis and Crystal Structure of Bis(tetraethylammonium) Octabromo‐triselenate(II)‐{dibromodiselenate(I)}, [NEt4]2[Se3Br8(Se2Br2)], the Salt of a Mixed‐valence Bromoselenate(II,I) Anion

The brown crystals of [NEt₄]₂[Se₃Br₈(Se₂Br₂)] ( 1 ) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of tetraethylammonium bromide. The crystal structure of 1 has been determined by the X‐ray methods and refined to R = 0.0308 for 10433 reflections. The crystals are monoclinic, space group P2₁ with Z = 2 and a = 12.0393(3) Å, b = 11.8746(3) Å, c = 13.1946(3) Å, β = 96.561(1)° (123 K). In the solid state structure the anion of 1 is built up of Se₃Br₈ unit which consists of a triangular arrangement of three planar SeBr₄ units sharing a common edge through two μ₃‐bridging Br atoms, and one Se₂Br₂ molecule which is linked to one of μ₃‐bridging Br atoms. The three Se^II atoms form a triangle which is almost perpendicular to the planes given by three SeBr₄ moieties. The contact between the μ₃Br and the Se^I atom of the Se₂Br₂ molecule is 3.1711(8) Å and can be interpreted as a bond of the donor‐acceptor type with the μ₃Br as donor and the Se₂Br₂ molecule as acceptor. The terminal Se^II‐Br and μ₃Br‐Se^II bond lengths are in the ranges 2.3537(7)–2.4737(7) Å and 2.7628(7)–3.1701(7) Å, respectively. The bond lengths in coordinated Se₂Br₂ molecule are: Se^I‐Se^I = 2.2636(9) Å, Se^I‐Br = 2.3387(11) and 2.3936(8) Å.     

Application of a chemical equilibrium model to thermodynamic functions of transfer of alcohols from water to aqueous surfactants

In ternary aqueous solutions, hydrophobic solutes such as alcohols tend to aggregate with surfactants to form mixed micelles. These systems can be studied by meas of the functions of transfer of hydrophobic solutes from water to aqueous solutions of surfactant. These thermodynamic functions often go through extrema in the critical micellar concentration (CMC) region of the surfactant. A simple model based on interactions between surfactant and hydrophobic solute monomers, on the distribution of the hydrophobic solute between water and the micelles and on the shift in the CMC induced by the hydrophobic solute, can simulate the magnitude and trends of the transfer functions using parameters which are mostly derived from the binary systems. In order to check the model more quantitatively, volumes and heat capacities of transfer of alcohols from water to aqueous solutions of a nonionic surfactant, octyldimethylamine oxide, were measured. A quantitative agreement was achieved with three adjustable parameters. Good fits are also obtained for the transfers to the ionic surfactants, octylamine hydrobromide and sodium dodecylsulfate. When the equilibrium displacement contribution is small, the distribution constants and the partial molar properties of the alcohols in the micellar phase agree well with the parameters obtained with similar models.     

Cluster synthesis. 42. The synthesis and crystal and molecular structures of the sulfur-bridged platinum-ruthenium carbonyl cluster compounds PtRu3(CO)9 L(PPh3)(μ3-S)2 (L=CO,PPh3) and PtRu4(CO)12(PPh3)(μ4-S)2

Two new mixed metal cluster complexes PtRu₃(CO)₁₀(PPh₃)(₃-S)₂,3 14% yield and PtRu₃(CO)₉(PPh₃)₂(₃-S)₂,4 23% yield were obtained from the reaction of Ru₃(CO)₉(₃-S)₂,1 with Pt(PPh₃)₂(C₂H₄) at 0°C. The cluster of4 consists of a spiked triangle of four metal atoms with two triply bridging sulfido ligands. The reaction of Ru₄(CO)₁₁(₄-S)₂,2 with Pt(PPh₃)₂(C₂H₄) yielded the expanded mixed-metal cluster complex PtRu₄(CO)₁₂(PPh₃)(₄-S)₂,5 in 12% yield. The structure of the cluster5 can be described as a pentagonal bipyramid of five metal atoms and two sulfido ligands with one metal-metal bond missing. Compounds4 and5 were characterized by a single-crystal X-ray diffraction analyses.     

Investigations on Chemical Vapour Transport of Intermetallic Phases in the System Co/Fe/Si

The ternary phases existing on the quasi binary section CoSi/FeSi and CoSi₂/β‐FeSi₂ have been investigated by solid state reactions and chemical transport. The solid solution serie Co_xFe_1‐xSi can be described as a regular solution. The transport behaviour calculated is in good agreement with the experiments. The phases have been characterized by X‐ray powder diffraction, EDX and ICP‐OES. The temperature dependence of the resistivity has been measured from 20 K up to room temperature on single crystals.     

Epoxide assisted sol-gel synthesis of rutile NixTi1-3xSb2xO2 solid solution nanoparticles

Rutile Ni _x Ti_1-3x Sb_2x O₂ solid solution nanoparticles were synthesized by a sol-gel route using propylene oxide as a gelation agent. Titanium oxide nanopowder and 12% TiCl₃ solution were used as the source for titanium to investigate the influence of the titanium precursors on the formation of the target materials. It was found that the nanoparticles prepared using 12% TiCl₃ solution showed a much lower phase formation temperature (700°C) as compared to those prepared from TiO₂ nanoparticles (1000°C). This lower phase formation temperature allowed a substantial reduction of the aggregation of the particles during calcination leading to the formation of nearly mono-dispersed nanoparticles of about 20 nm. The results of this work show that the epoxide assisted sol-gel method is capable to produce titanium-based ternary oxide solid solution nanoparticles, owing to the formation of a highly homogeneous precursor gel intermediate.     

Photophysical characterization of mixed micelles of n-butanol/SDS and n-hexanol/SDS. A study at low alcohol concentrations

 The effect of the addition of n-butanol (BuOH) and n-hexanol (HexOH) on the micellization of sodium dodecylsulfate (SDS) has been investigated using fluorescence quenching methods. The binding constants were calculated using an expression which relates the total concentration of alcohols and the micelle concentration. The values of K were 4.67 and 17.6 M^-1 for BuOH/SDS and HexOH/SDS, similar to values obtained by other methods. The cmc of SDS decreases on addition of alcohols and goes through a minimum for the BuOH/SDS system. Micellar aggregation numbers (N) were determined from linear plots of Ln (I ⁰/I) against [Quencher] at low alcohol concentrations. For 15 mM SDS, in the presence of BuOH the N values decrease on addition of alcohol up to 0.2 M. For HexOH, N can be assumed to be constant up to 4.8 mM, after which N decreases. The polarity of the micellar core containing alcohol was evaluated from the I ₁/I ₃ ratio of monomeric pyrene. The effect of addition of the alcohol causes a decrease in the I ₁/I ₃, which corresponds to a decrease in the polarity of the pyrene solubilization site. Received: 28 October 1996 Accepted: 10 January 1997     

超导体Y-Ba-Cu-O复合氧化物催化苯酚羟化反应的研究

利用HZOZ和苹酚联产对苯二醋和邻苯二酚是目前二酚生产领域中比较活跃的课题．长久以来，人们曾利用酸、金属盐、金属配合物等作为催化剂，在均相体系中来研究其对苯酸羟化反应的催化活性．由平均相反应存在着明显的缺点，后来又转向了多相催化剂的开发，先后出现了TSull］TS42     

The mixed valent tellurate SrTe3O8: Electronic lone pair effect of Te

A novel mixed valent tellurium oxide, SrTe₃O₈, has been synthesized and its crystal structure was determined ab initio from powder X-ray diffraction data. This oxide, which crystallizes in a tetragonal unit-cell, P4₂/m space group, with very close a and c cell parameters (6.8257(1) and 6.7603(1) Å, respectively), exhibits a very original structure built up of corner-sharing TeO₆ (Te⁶⁺) octahedra and Te₂O₈ (Te⁴⁺) twin-pyramidal units. The latter ones form [Te₃O₈]_∞ chains running along the [001] and the [110] directions. Besides the four sided tunnels where the Sr²⁺ cations are located, there are very large four sided tunnels running along the c-axis which are obstructed by the electronic lone pairs of the Te⁴⁺ cations.     

A new platinum-osmium alkyne complex from the reaction of Pt2Os4(CO)18 with PhC ≡ CPh: The synthesis,characterization, and crystal structure of Pt2Os4(CO)8 (μ3-PhC2Ph)3(μ4-PhC2Ph)

The new platinum-osmium alkyne cluster complex Pt₂Os₄(CO)₈(₃-PhC₂Ph)₃ ( ₄-PhC₂Ph),2, was obtained from the reaction of Pt₂Os₄(CO)₁₈,1b, with PhC₂Ph and was characterized by IR.¹H NMR and single-crystal X-ray diffraction analyses. The cluster of compound2 consists of an osmium capped Pt₂Os₃ square pyramid. It aLso contains three triply bridging and one quadruply bridging diphenylacetylene ligands. Crystal data for2: space group PI,a = 12.530(2) Å,b = 21.565(4) Å,c = 11.284(2) Å, = 100.31(2), = 111.89(1), = 76.78(2),Z = 2, 3879 reflections,R = 0.032.