Laser Microprobe Mass Analysis of NH4 ReO4, AgReO4 and Al (ReO4)3

The laser microprobe mass analyzer (LAMMA) is a recently developed mass spectroscopic technique for both organic and inorganic microanalysis. LAMMA analysis involves laser ionization of the sample material followed by mass separation in a time of flight (TOF) mass spectrometer. The present application of LAMMA illustrates the characterization of three inorganic perrhenates: NH₄ReO₄, AgReO₄ and Al(ReO₄)₃. Results clearly show the value of LAMMA for inorganic mass spectrometry, in this study the most useful data originated in the negative-ion mass spectra.     

Raman analysis of perrhenate and pertechnetate in alkali salts and borosilicate glasses

Sodium borosilicate glasses containing rhenium or technetium were fabricated and their vibrational spectra studied using confocal Raman microscopy. Glass spectra were interpreted relative to new high‐resolution spectra of pure crystalline NaReO₄, KReO₄, NaTcO₄, and KTcO₄ salts. Spectra of perrhenate and pertechnetate glasses exhibited sharp Raman bands, characteristic of crystalline salt species, superimposed on spectral features of the borosilicate matrix. At low concentrations of added KReO₄ or KTcO_4, the characteristic pertechnetate and perrhenate features are weak, whereas at high additions, sharp peaks from crystal field‐splitting and C_4h symmetry dominate glass spectra, clearly indicating ReO₄⁻ or TcO₄⁻ is locally coordinated with K and/or Na. Peaks indicative of both K and Na salts are evident in many Raman spectra, with the Na form being favored at high concentrations of the source chemicals, where more K⁺ is available for ion exchange with Na⁺ from the base glass. The observed ion exchange likely occurred within depolymerized channels where nonbridging oxygens create segregation from the glass network in regions containing anions such as ReO₄⁻ and TcO₄⁻ as well as excess alkali cations. Although this anion exchange provides evidence of chemical mixing in the glass, it does not prove the added salts were homogeneously incorporated in the glass. The susceptibility to ion exchange from the base glass indicates that long‐term immobilization of Tc in borosilicate glass must account for excess charge compensating alkali cations in melt glass formulations. Published 2014. This article is a U. S. Government work and is in the public domain in the USA.     

咪唑类高铼酸盐催化微晶纤维素降解反应研究

以咪唑类高铼酸盐为催化剂,以离子液体1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)为溶剂降解微晶纤维素(MCC)。分别考察反应温度、反应时间、反应物浓度、催化剂用量和结构对纤维素降解反应的影响。结果表明,以5%1-(3-磺酸)丙基-3-甲基咪唑高铼酸盐([mim-(CH_2)_3SO_3H]ReO_4)为催化剂,在微波辅助加热条件下,0.1 g纤维素在2.0 g离子液体[Amim]Cl中于160℃降解30 min,还原糖收率(TRS)和葡萄糖收率最高可达89.6%和46.7%。研究还对咪唑类高铼酸催化纤维素降解反应的催化机理进行讨论,认为催化剂芳环阳离子、ReO-4中Re=O与纤维素分子中羟基的相互作用是促进纤维素降解的关键     

Synthesis and structure determination of copper perrhenate, CuReO4

Copper(I) perrhenate, CuReO₄, has been synthesized as a single-phase sample in sealed silica tubes at 500-800 °C, and its structure was determined for the first time by single-crystal X-ray diffraction. CuReO₄ forms a new structure type derived from the diamond-structure and crystallizes in space group I4₁cd with lattice parameters a=13.6965(5) Å and c=7.7729(5) Å, Z=16 (rotation method data acquisition using ω and ? scans, R₁=0.0191, wR₂=0.0403). Cu and Re atoms are tetrahedrally coordinated by O atoms, these tetrahedra are corner-shared, forming spirally twisted rings of 4-6-8-10-MeO₄ like Si_xO_y-rings in some silicon dioxide modifications or aluminosilicates. According to low-temperature powder X-ray diffraction and differential thermal analysis, CuReO₄ shows no phase transition down to 80 K and up to its melting point, 703 K.     

Osmotic and activity coefficients of aqueous NaTcO4 and NaReO4 solutions at 25°C

Isopiestic vapor-pressure comparison experiments were performed with aqueous binary sodium perchlorate, pertechnetate, and perrhenate solutions to concentrations of approximately 8.5 m. Osmotic coefficients for these solutions and mean molal ionic activity coefficients for NaTcO₄ and NaReO₄ were derived from the isotonic molalities. Pitzer's treatment was applied to describe the concentration dependence of the osmotic coefficients of NaClO₄, NaTcO₄, and NaReO₄, and the implications of the parameters derived from a leastsquares fit are discussed in terms of solvent structure and interionic forces.     

Raman Investigation of the Low Temperature Phase Transitions in Monoclinic TlReO4

The Raman spectrum of monoclinic TlReO₄ is presented together with a factor group analysis and assignment of the bands. The phase transitions of monoclinic TlReO₄ is investigated below room temperature, and two phase transitions were identified between room temperature and 90 K. The room temperature monoclinic phase was converted to the orthorhombic phase at 170 K upon cooling, and to the tetragonal phase at 150 K. Upon heating back to room temperature the tetragonal phase persisted until the orthorhombic phase could be identified at 210 K and 220 K. From 230 K to room temperature the monoclinic phase could again be observed.     

高铼酸钙与PETE基础油的复配及其宽温度范围减摩性能

优选出将Ca(ReO4)2粉末长期稳定分散在季戊四醇脂(PETE)基础油中的表面活性剂体系及其含量,制备出含Ca(ReO4)2成分的PETE复配油品.考察了油品从室温到600℃对Si3N4球/GH128盘摩擦副的润滑能力.结果表明:OP-10加SDS的表面活性剂体系具有超过90天的稳定分散效果,Ca(ReO4)2质量百分数为0.5%~1.0%的PETE复配润滑油,在宽温度范围具有良好的减摩效果,全程摩擦系数保持在0.15~0.25.讨论了从油润滑平稳过渡到固体薄膜润滑的混杂润滑模式的作用机理.     

Structure and thermal properties of [RhPy4Cl2]X complex salts (X = Cl?, ReO 4? , ClO 4? )

[RhPy₄Cl₂]Cl·4H₂O (I), [RhPy₄Cl₂]ReO₄ (II), [RhPy₄Cl₂]ClO₄ (III), and [RhPy₄Cl₂]ReO₄·2H₂O complex salts were synthesized. The crystal structure of compounds II (P4/ncc, a = 25.5655(3) ?, c = 14.3521(4) ?), III (P2₁/n, a = 13.5308(3) ?, b = 15.1044(5) ?, c = 23.3457(8) ?, β = 93.327°), and dyhydrate of II (Pbcm, a = 10.6199(9) ?, b = 10.4964(9) ?, c = 22.9834(16)?) was determined by X-ray diffraction analysis. The thermal transformations of the complexes were studied by differential thermal analysis. The substances were characterized by IR spectroscopy, XRPA, and element analysis Original Russian Text Copyright ? 2009 by D. B. Vasilchenko, I. A. Baidina, E. Yu. Filatov, and S. V. Korenev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 349–356, March–April, 2009.     

Electrochemical and Spectroelectrochemical Properties of Poly-<Emphasis Type="Italic">o</Emphasis>-phenylenediamine: The Effect of the Perrhenate Anion

Poly-o-phenylenediamine films applied to ITO are modified by rhenium oxides using cyclic voltammetry in an ammonium perrhenate sulfate solution. Electrochemical and spectroelectrochemical properties of the composite thus obtained are studied. It is shown that all its components undergo reversible redox conversion.     

Osmotic and activity coefficients of perrhenic acid and perrhenate salts

Osmotic and activity coefficients are reported for the aqueous solution of perrhenic acid and for its lithium, sodium and tetramethylguanidinium slats at 25°C. These coefficients are similar in order of magnitude but smaller than the coefficients of the corresponding perchorates. Evidence is submitted for the ion pairing of the perrhenate ion with both hydronium and tetramethylguanidinium ions in fairly dilute aqueous solutions. The association with hydronium ion decreases in more concentrated solutions.