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91.
92.
Monir Uddin Antonis G. Hatzidimitriou Maria Lalia-Kantouri Chris Tsiamis 《Structural chemistry》1997,8(2):131-139
The infrared and electronic excitation spectra of a series of new nickel(II) chelates containing an-diimine (or nitrogenous base, enR) and the anion of a-dione (1,3-ketoenol or 1,3-ketoester,H) were obtained in the solid state and in solution. The composition and the overall structure of the new chelates in the solid state depends on ligand concentration, the substituents within the-dionato moiety and the counterion present. The IR and electronic excitation spectra of [Ni(enR)2
]NO3 and [Ni(enR)(O2NO)] indicate, in conjunction with other physicochemical measurements, bidentate coordination of the ligands, while the spectral shifts reveal replacement of the (O,O)nitrato group by basic solvents. The existence of the nickel(II) in an octahedral environment is confirmed by an X-ray structure analysis of [Ni(dpamH)2acac]NO3 · CH3OH (monoclinic, space groupP2l/n, a=17.296(1),b=7.462(1),c=21.604(3) å,=95.65(1),Z=4, R=0.0534,Rw=0.0600), where dpamH denotes the 2,2-dipyridylamine. 相似文献
93.
新试剂5-(4-氯苯基偶氮)-8-苯磺酰氨基喹啉光度法测定微量铜 总被引:5,自引:0,他引:5
在 p H 8.5的 Na2 B4 O7- HCl介质及有氯化十六烷基吡啶 ( CPC)存在时 ,室温下铜 ( )与 5 - ( 4 -氯苯基偶氮 ) - 8-苯基磺酰氨基喹啉 ( CPBSQ)迅速反应 ,生成络合比为 1∶ 3的有色络合物。研究了反应的最佳条件 ,建立了一个测定 Cu( )的光度分析新方法。Cu( )的浓度在 0~ 1 4.0 μg/2 5 m L 范围内符合比耳定律 ,其摩尔吸光系数为 8.1 2× 1 0 4 L· mol- 1· cm- 1。方法用于面粉、茶叶及奶粉中铜的测定 ,其相对标准偏差为 0 .5 8%~ 1 .2 % ,标准加入回收率为 95 .5 %~ 1 0 4 .5 %。 相似文献
94.
Smetanina O. F. Kuznetzova T. A. Denisenko V. A. Pivkin M. V. Khudyakova Yu. V. Gerasimenko A. V. Popov D. Yu. Il"in S. G. Elyakov G. B. 《Russian Chemical Bulletin》2001,50(12):2463-2465
A pentacyclic tritepenoid, 3-methoxyolean-18-ene (miliacin), was isolated for the first time from the marine fungus Chaetomium olivaceum. Its structure was determined on the basis of 2D NMR spectroscopy and X-ray diffraction data. 相似文献
95.
LaCoO3 perovskite was prepared at 700°C using citrate precursors. The product was then characterized with X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). The powder XRD pattern indicates rhombohedral or its monoclinic I2/a subgroup symmetry. The electronic configuration and the short-range atomic structure of the LaCoO3 perovskite at room temperature were investigated using synchrotron near-edge X-ray absorption spectroscopy (XANES) and extended X-ray absorption spectroscopy (EXAFS). From the XANES region of the XAS we conclude that Co(III) is at least partly in its intermediate- or high-spin state, which is in accordance with most of the published literature on LaCoO3 perovskite. The EXAFS region of the LaCoO3 perovskite spectrum, which up to now was almost not investigated, was simulated satisfactorily for the first two radial structure peaks in terms of the dominant scattering contributions generated with the FEFF8 code and the structural information available from crystallographic data. The best simulation results were obtained with I2/a symmetry. The obtained amplitude reduction factor, zero-energy shift and Debye-Waller factors are useful reference values for data analyses of similar compounds like partly substituted LaCoO3 perovskite, such as La1−xCaxCoO3 or La1−xSrxCoO3, which are materials of technical interest in catalyst and other applications. 相似文献
96.
新显色剂1-羟基-2-(5-NO2-2-吡啶偶氮)-8-氨基-3,6-萘二磺酸与铜显色反应的研究 总被引:3,自引:0,他引:3
探讨了新显色剂 1-羟基-2-(5-NO2-2-吡啶偶氮)-8-氨基-3,6-萘二磺酸(简称5-NO2-PAH)与铜离子显色的适宜条件及其共存离子的影响,建立了 5-NO2-PAH测定铜的新显色反应体系.在 pH 7.0~10.0 范围内,铜与试剂形成稳定的 1∶2 配合物,其最大吸收峰位于 653 nm, 表观摩尔吸光系数εCu=4.68×104 L·mol-1·cm-1,铜的浓度在 0 μg/10 mL~14 μg/10 mL 范围内遵守比尔定律.方法已用于合金中铜的测定. 相似文献
97.
Pb8FeIIFeF24 is triclinic: a = 20.118(3) Å, b = 5.597(1) Å, c = 9.440(2) Å, α = 89.75(2)°, β = 105.79(2)°, α = 89.38(2)°, Z = 2. The structure is solved in the unconventional space group C1 , from X-ray single crystal data using 1 641 independent reflections (R = 0.048, Rw = 0.051). It is built up from the stacking of two subnetworks along the a axis: fluorite-like [Pb8F10]n6n+ layers and infinite dimetallic [FeIIFeF14]n6n? double-chains of corner-sharing octahedra running along the b axis. 相似文献
98.
An analytical scheme is proposed which combines three speciation techniques for determination of particular Al species in soil extracts and percolating waters. A cation-exchange fast protein liquid chromatography — inductively coupled plasma atomic emission spectrometry (FPLC-ICP-AES) procedure, a microcolumn chelating ion-exchange chromatography- atomic absorption spectrometry (MCC-ETAAS) technique and the 8-hydroxyquinoline spectrophotometric method (8HQ-spectrophotometry) were employed. The FPLC-ICP-AES procedure offers determination of Al3+ (retention time 4.5 min) and Al(OH)2+ species (retention time 4.0 min) which are separated from Al(OH)+
2 (retention time 1.5min). AlF2+ coelutes with Al(OH)2+ species, while Al(SO4)+, AlF+
2 and negatively charged Al organic complexes coelute with Al(OH)+
2 species. The MCC-ETAAS technique enables determination of the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphate- and fluoro-Al complexes. Employing the 8HQ-spectrophotometry the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphato- and most of the labile organic Al species are determined. The sensitivities of these selected techniques were adequate for speciation of Al in the samples analyzed. On the basis of the specific selectivity of a particular technique various groups of Al species may be determined. Thus, the comparison of analytical data from complementary procedures provides more comprehensive information on Al species present in soil extracts and percolating waters. 相似文献
99.
D. Y. Ye 《Journal of Optimization Theory and Applications》1993,76(2):287-304
LetA(·) be ann × n symmetric affine matrix-valued function of a parameteruR
m
, and let (u) be the greatest eigenvalue ofA(u). Recently, there has been interest in calculating (u), the subdifferential of atu, which is useful for both the construction of efficient algorithms for the minimization of (u) and the sensitivity analysis of (u), namely, the perturbation theory of (u). In this paper, more generally, we investigate the Legendre-Fenchel conjugate function of (·) and the -subdifferential (u) of atu. Then, we discuss relations between the set (u) and some perturbation bounds for (u).The author is deeply indebted to Professor J. B. Hiriart-Urruty who suggested this study and provided helpful advice and constant encouragement. The author also thanks the referees and the editors for their substantial help in the improvement of this paper. 相似文献
100.