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81.
N. V. Bausk S. B. Érenburg L. G. Lavrenova L. N. Mazalov 《Journal of Structural Chemistry》1995,36(6):925-931
EXAFS spectroscopy is used to investigate the characteristic features of the spatial and electronic structure of the polynuclear Fe(II) complexes Fe(ATR)3A2 (where A is the NO 3 ? , BF 4 ? , Br?, or ClO 4 ? anion and ATR is 4-amino-1,2,4-triazole) and their magnetically diluted phases FexZn1?x(ATR)3(NO3)2. The absolute distances from Fe and Zn to the surrounding atoms are determined at temperatures higher and lower than the spin transition point. In all complexes, the spin transition is accompanied by significant changes in the local environment of Fe atoms, while in the magnetically diluted phases the surrounding of zinc remains unchanged. It is shown that addition of Zn atoms distorts the triazole rings in the low-spin state of the complexes. No localized anions were revealed within 3.3 Å from the Fe and Zn atoms. It is shown that a decrease in the spin transition temperature correlates with an increase in Fe?N distances in the low-spin complexes due to magnetic dilution and substitution of anions in the series NO 3 ? , BF 4 ? , Br?, ClO 4 ? of ATR-containing complexes. 相似文献
82.
A. F. Rukasov S. P. Épshtein V. P. Tashchi Yu. A. Baskakov Yu. G. Putsykin 《Chemistry of Heterocyclic Compounds》1984,20(3):323-325
The corresponding 4-(O-carbamoylhydroxyamino)imidazolidin-2-ones were obtained by cyclization of O,N-dicarbamoyl derivatives of N-(3-oximino-2-methyl-2-butyl)- and N-(1-oximino-2-cyclohexyl)methylamines in alkaline media. It was shown that the carbamoylation of 1-methyl-4,5-tetramethylene-3-(3,4-dichlorophenyl)-4-hydroxy-aminoimidazolidin-2-one gives, respectively, an O- or N-carbamoyl derivative, depending on whether it is carried out in alkaline or neutral solutions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 399–401, March, 1984. 相似文献
83.
84.
S. B. Érenburg L. N. Mazalov N. V. Bausk M. K. Drozdova 《Journal of Structural Chemistry》1994,35(4):517-522
SKα, SKβ, ClKβ, ClKβ, and PdLβ2 X-ray fluorescent and PdK EXAFS spectra were obtained for some organic solutions of dialkyl sulfide complexes with palladium
chloride. Solvent effects on the electronic and spatial structure of complexes in solution are discussed. In the benzene solution
of [PdCl22(C6H13)2S], complex molecules interact with solvent molecules along a coordinate that is perpendicular to the plane of the complex
molecule.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 4, pp. 105c111, July–August, 1994.
Translated by L. Smolina 相似文献
85.
Érika Pinto Marinho A. G. Souza Danniely S. de Melo Iêda M. G. Santos Dulce M. A. Melo Walquíria J. da Silva 《Journal of Thermal Analysis and Calorimetry》2007,87(3):801-804
Because
of their electrical, magnetic and catalytic properties rare earth and transition
metal mixed oxides are important compounds. Lanthanum chromites have been
extensively used as solid oxide fuel cell (SOFC) interconnect materials. In
this work, lanthanum chromites partially substituted by alkaline earth metals
were synthesized by the urea combustion process. TG and DSC techniques were
used to evaluate the presence of the organic material in the powder after
reaction on the hot plate. The powders were calcinated at 900°C and characterized
by XRD and SEM. The results show that the particles have nanometric dimensions
and the perovskite structure was formed. 相似文献
86.
A Bis(pyridine N‐oxide) Analogue of DOTA: Relaxometric Properties of the GdIII Complex and Efficient Sensitization of Visible and NIR‐Emitting Lanthanide(III) Cations Including PrIII and HoIII 下载免费PDF全文
Henrique F. Carvalho Dr. João M. C. Teixeira Carlos T. B. Paula Prof. Petr Hermann Dr. Carlos Platas‐Iglesias Prof. Stephane Petoud Prof. Éva Tóth Prof. Carlos F. G. C. Geraldes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14834-14845
We report the synthesis of a cyclen‐based ligand (4,10‐bis[(1‐oxidopyridin‐2‐yl)methyl]‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid= L1 ) containing two acetate and two 2‐methylpyridine N‐oxide arms anchored on the nitrogen atoms of the cyclen platform, which has been designed for stable complexation of lanthanide(III) ions in aqueous solution. Relaxometric studies suggest that the thermodynamic stability and kinetic inertness of the GdIII complex may be sufficient for biological applications. A detailed structural study of the complexes by 1H NMR spectroscopy and DFT calculations indicates that they adopt an anti‐Δ(λλλλ) conformation in aqueous solution, that is, an anti‐square antiprismatic (anti‐SAP) isomeric form, as demonstrated by analysis of the 1H NMR paramagnetic shifts induced by YbIII. The water‐exchange rate of the GdIII complex is ${k{{298\hfill \atop {\rm ex}\hfill}}}$ =6.7×106 s?1, about a quarter of that for the mono‐oxidopyridine analogue, but still about 50 % higher than the ${k{{298\hfill \atop {\rm ex}\hfill}}}$ of GdDOTA (DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). The 2‐methylpyridine N‐oxide chromophores can be used to sensitize a wide range of LnIII ions emitting in both the visible (EuIII and TbIII) and NIR (PrIII, NdIII, HoIII, YbIII) spectral regions. The emission quantum yield determined for the YbIII complex (${Q{{{\rm L}\hfill \atop {\rm Yb}\hfill}}}$ =7.3(1)×10?3) is among the highest ever reported for complexes of this metal ion in aqueous solution. The sensitization ability of the ligand, together with the spectroscopic and relaxometric properties of its complexes, constitute a useful step forward on the way to efficient dual probes for optical imaging (OI) and MRI. 相似文献
87.
Some asymptotic results are proved for the distribution of the maximum of a centered Gaussian random field with unit variance on a compact subset S of
N
. They are obtained by a Rice method and the evaluation of some moments of the number of local maxima of the Gaussian field above an high level inside S and on the border S. Depending on the geometry of the border we give up to N+1 terms of the expansion sometimes with exponentially small remainder. Application to waves maximum is shown. 相似文献
88.
N. B. Éshkobilov 《Journal of Applied Spectroscopy》2002,69(3):477-479
The main series of a silver atom with n = 5–70 are investigated. Perturbations of the np
2
P
1/2,3/2 states with n = 10 and 17 caused by interaction with the selfionization 4d5s5p
4
P
1/2,3/2 states are detected. Energies of the selfionization states are determined. 相似文献
89.
V. A. Zamureenko N. A. Klyuev L. B. Dmitriev I. I. Grandberg G. A. Ésvandzhiya 《Chemistry of Natural Compounds》1984,20(6):681-683
The composition of the terpenoid and sesquiterpene hydrocarbon fraction ofSalvia garedzhii has been studied by chromato-mass spectrometry. A total of 19 compounds have been identified and a provisional assignment of another 6 components has been made. 相似文献
90.