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91.
K3MnH5, the First Salt-like Manganese Hydride K3MnH5 and K3MnD5 were synthesized by the reaction of potassium hydride (deuteride) with manganese powder under a hydrogen pressure above 3000 bar at 875 K. X-ray investigations on powdered samples and elastic neutron diffraction experiments on the deuterated compound at the time-of-flight spectrometer LAD in the temperature range 5–600 K led to the complete structure determination. The atomic arrangement is isotypic with that of Cs3[CoCl4]Cl (space group: 14/mcm, Z = 4). The structure of K3MnH5 contains isolated [MnH4]2?-tetrahedra and additional hydrogen ions which are exclusively coordinated by potassium cations. The magnetic susceptibilities show Curie-Weiss behaviour. At temperatures below 50 K there are obviously antiferromagnetic interactions. 相似文献
92.
V. S. Lenenko P. Kränke M. Wahren V. B. Shur M. E. Vol'pin 《Russian Chemical Bulletin》1995,44(7):1293-1299
The interaction of labeled dinitrogen complexescis-(Me2PhP)4Mo(15N2)2 andtrans-(dppe)2W(15N2)2 with non-labeled nitronium and nitrosonium fluoroborates,14NO2BF4 and14NOBF4, in sulfolane at room temperature in the presence of H2SO4 results in rapid formation of labeled nitrous and nitric oxides (15N14NO,15NO), as well as15N14N. The yield of the products depends on the reagent ratio and reaches 10–20 mol. % per mole of a complex under optimum conditions. The mechanism of the reactions found is proposed. It involves the step of protonation of the dinitrogen ligand to form the corresponding hydrazido(2–) derivatives, which are then attacked by nitronium or nitrosonium cations. In accordance with the mechanism proposed, it was established that the hydrazido(2–) complexes, (Me2PhP)3Mo(15N2H2)Cl2 and (dppe)2W(15N2H2)Cl2, are capable of forming15N14NO,15NO, and15N14N under the action of14NO2BF4 and14NOBF4 in the absence of an acid.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 13–13, July, 1995. 相似文献
93.
催化褪色光度法测定微量锰(Ⅱ)的研究 总被引:6,自引:2,他引:6
本文研究在硫酸介质中,锰(Ⅱ)催化EDTA还原重铬酸银,而使之褪色的新指示反应。确定了催化褪色反应动力学条件,锰(Ⅱ)的浓度在0-0.4μg/ml范围内,工作曲线呈良好的线性关系,检测限为0.011μg/mL,该方法用于天然水及污水中锰的测定,获得满意结果。 相似文献
94.
Modern condensed-matter physics is increasingly concerned with the design, synthesis, analysis, and exploitation of chemically complex materials and structures. Complex metal oxides and strongly correlated electron systems such as YBa2Cu3O7−x and La1−xSrxMnO3 are paradigmatic examples. Their production in the form of high-quality thin films is of both technological and fundamental importance and has stimulated a concerted effort in the last two decades to find and optimize efficient techniques to this end. This review discusses the physics behind and the requirements for synthesizing high-quality films of such materials and examines fundamental aspects of the growth processes associated with magnetron sputtering and pulsed laser deposition, the two techniques which presently offer the best solutions in this burgeoning field. 相似文献
95.
Addition of amines to pyranosyl nitrile oxides, generated by base-induced dehydrochlorination of the corresponding hydroximoyl chloride, affords pyranosyl N-alkyl/aryl-formamide oximes (41-90%). Reaction with amino acid esters yields the corresponding amidoximes and/or 3-pyranosyl-1,2,4-oxadiazin-6-ones. The structure of N-phenyl-C-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)formamide oxime was established by X-ray crystallography. 相似文献
96.
纳米多孔双金属氧化物在镍钛合金纤维上的原位生长及其对多环芳烃的选择性固相微萃取 总被引:1,自引:0,他引:1
采用阳极氧化法在镍钛合金(NiTi)纤维上原位生长了双金属氧化物纳米孔(NiTiONPs)涂层,通过扫描电镜(SEM)和能谱(EDS)考察了电解质组成和电压对形貌的影响。将NiTiONPs涂层的NiTi纤维与高效液相色谱-紫外检测器联用,研究了4种典型芳香分析物的萃取性能。结果表明,富含TiO2的NiTiONPs涂层对多环芳烃(PAHs)具有良好的萃取效率,尤其对苯并[a]芘的萃取选择性优于市售聚二甲基硅氧烷纤维和聚丙烯酸酯纤维。在优化条件下,PAHs的线性范围为0.05~200μg/L,相关系数均大于0.999,检出限为0.012~0.134μg/L。对单支纤维日内和日间分析的相对标准偏差(RSDs)分别为4.0%~5.5%和6.0%~6.8%,使用分批组装的5支纤维分析的RSDs为6.4%~7.6%。实际水样分析的加标回收率为84.5%~111.5%。所制备NiTi纤维至少可重复使用250次以上,重现性好。 相似文献
97.
Wolfdieter A. Schenk 《Angewandte Chemie (International ed. in English)》1987,26(2):98-109
Donor molecules undergo dramatic changes in their chemical properties on coordination to a transition-metal atom. Highly reactive species can be trapped and studied as ligands. Conversely, stable compounds can be activated to undergo novel reactions. Sulfur dioxide complexes have generally been studied from a structural viewpoint, their reactivity having been somewhat neglected. The unstable sulfur oxides SO, S2O, and S2O2 are still often regarded as laboratory curiosities. Their successful stabilization in transition-metal complexes has now made them accessible to detailed study, in the course of which many relationships to the chemistry of SO2 complexes have become apparent. 相似文献
98.
Feth MP Bolm C Hildebrand JP Köhler M Beckmann O Bauer M Ramamonjisoa R Bertagnolli H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(6):1348-1359
XANES and EXAFS spectroscopic studies at the Mn-K- and Br-K-edge of reaction products of (S,S)-(+)-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminomanganese(III) chloride ([(salen)Mn(III)Cl], 1) and (S,S)-(+)-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminomanganese(III) bromide ([(salen)Mn(III)Br], 2) with 4-phenylpyridine N-oxide (4-PPNO) and 3-chloroperoxybenzoic acid (MCPBA) are reported. The reaction of the Mn(III) complexes with two equivalents of 4-PPNO leads to a hexacoordinated compound, in which the manganese atom is octahedrally coordinated by four oxygen/nitrogen atoms of the salen ligand at an average distance of approximately 1.90 A and two additional, axially bonded oxygen atoms of the 4-PPNO at 2.25 A. The oxidation state of this complex was determined as approximately +IV by a comparative study of Mn(III) and Mn(V) reference compounds. The green intermediate obtained in reactions of MCPBA and solutions of 1 or 2 in acetonitrile was investigated with XANES, EXAFS, UV/Vis, and Raman spectroscopy, and an increase of the coordination number of the manganese atoms from 4 to 5 and the complete abstraction of the halide was observed. A formal oxidation state of IV was deduced from the relative position of the pre-edge 1s-->3d feature of the X-ray absorption spectrum of the complex. The broad UV/Vis band of this complex in acetonitrile with lambda(max)=648 nm was consistent with a radical cation structure, in which a MCPBA molecule was bound to the Mn(IV) central atom. An oxomanganese(V) or a dimeric manganese(IV) species was not detected. 相似文献
99.
Yu. V. Mironov S. F. Solodovnikov V. E. Fedorov Yu. V. Gatilov 《Journal of Structural Chemistry》2004,45(5):874-878
The reaction of a water solution of K4Re6Te8(CN)6 with a solution of Mn(NO3)2 in 0.02M hydrochloric acid in the presence of DMF gave crystals of a cluster rhenium complex [{ Mn(H2O)2(DMF)}2Re6Te8(CN)6]·2H2O. The structure of the compound was determined by single crystal X-ray diffraction (a = 12.6679(9) Å, b = 17.4524(12) Å, c = 9.7882(6) Å, β = 105.570(6)°, V = 2084.6(3) Å3, Z = 2, space group P21/n, R = 0. 0389). In the complex, the [Re6Te8(CN)6]4− cluster anions are linked to Mn2+ cations by the cyanide bridges, the manganese cations being additionally coordinated by the DMF molecule and two water molecules. The neighboring clusters are joined by Re-C-N-Mn bridges into a three-dimensional framework possessing cavities filled with doubly disordered water molecules.Original Russian Text Copyright © 2004 by Yu. V. Mironov, S. F. Solodovnikov, V. E. Fedorov, and Yu. V. Gatilov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 918–922, September–October, 2004. 相似文献
100.