Reactions of CsI and HgI2 with benzo-15-crown-5 (B15C5) and 15-crown-5 (15C5) in an ethanol-acetone mixture produced [Cs(B15C5)2]2[Hg2I6] (1) and {[Cs(15C5)]2[Hg2I6]}n (2), respectively. The structures of the two complexes are quite different. Molar ratios of Cs+ : crown ether are 1 : 2 in 1 and 1 : 1 in 2. Complex 1 consists of two Cs(B15C5)
2+
cations and a Hg2I
62-
anion. Cs+ lies between the two crown-5 ligands, resulting in a sandwich-type cation. Cationic Cs(B15C5)
2+
and anionic Hg2I
62-
are linked together by electrostatic interactions and the complex 1 is an ion pair compound. Complex 2 consists of infinite [Cs(15C5)]2[Hg2I6] units. Each structural unit contains two Cs(15C5)+ cations and a Hg2I
62-
anion. Cs+ is coordinated by five oxygen atoms of 15C5, three iodine atoms of Hg2I
62-
, and an iodine atom of Hg2I
62-
in an adjacent structural unit. The interactions between the Cs+ of Cs(15C5)+ and an I– in Hg2I
62-
from adjacent structural units polymerize the complex 2, resulting in a one-dimensional network structure. The anions of Hg2I
62-
in both complexes are similar. The two mercury atoms are linked through two bridging iodine atoms and each mercury is also coordinated by two terminal iodines. Crystal data for 1: space group P21/c (No. 14), a = 12.253(4), b = 20.945(7), c = 16.110(6) Å, = 111.0(1)°, V = 3860 Å3, Z = 4, R = 0.082 (Rw = 0.089). Crystal data for 2: space group P21/c (No. 14), a = 12.157(4), b = 8.546(4), c = 20.666(6) Å, = 91.54(3)°, V = 2146 Å3, Z = 4, R = 0.034 (Rw = 0.048). 相似文献
The chromatographic performance of the deuterated solvents, CD3OD and D2O, has been investigated in reversed-phase micro high performance liquid chromatography. The chromatographic performance of CD3OD is only slightly superior to that of CH3OH. However, the performance of D2 is significantly superior to that of H2O, separation of aromatics being improved by about 30%. D2 is a particularly powerful solvent for the separation iof deuterated and non-deuterated compounds. 相似文献
Cyclocondensation of 2-arylmethylidene-3-fluoroalkyl-oxopropionates with 2-amino-pyridine occurs at both the polyfluoroacylvinyl
and alkoxycarbonylvinyl fragments to give alkyl 4-aryl-2-polyfluoroalkyl-4H-pyrido[1,2-a]pyrimidine-3-carboxylates and 4-aryl-2-hydroxy-3-polyfluoroacyl-4H-pyrido[1,2-a]pyrimidines, respectively. When treated with copper(II) acetate, the pyrido[1,2-a]pyrimidines yield metal complexes.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2745–2749, December, 2005. 相似文献
The reaction of alkyl 4-(2-acetylhydrazino)-2-methyl-3-thiophenecarboxylates with 3-methylbutan-2-one was carried out under the Fischer reaction conditions. The influence of Lewis acids and solvents on the process was studied. A convenient method for the synthesis of thieno [3.2-b]pyrrolenine derivatives was proposed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 725–729, March, 2005. 相似文献
In recent years, the self-assembled growth of semiconductor nanostructures, that show quantum size effects, has been of considerable interest. Laser devices operating with self-assembled InAs quantum dots (QDs) embedded in GaAs have been demonstrated. Here, we report on the InAs/GaAs system and raise the question of how the shape of the QDs changes with the orientation of the GaAs substrate. The growth of the InAs QDs is understood in terms of the Stranski–Krastanow growth mode. For modeling the growth process, the shape and atomic structure of the QDs have to be known. This is a difficult task for such embedded entities.
In our approach, InAs is grown by molecular beam epitaxy on GaAs until self-assembled QDs are formed. At this point the growth is interrupted and atomically resolved scanning tunneling microscopy (STM) images are acquired. We used preparation parameters known from the numerous publications on InAs/GaAs. In order to learn more about the self-assemblage process we studied QD formation on different GaAs(0 0 1), (1 1 3)A, and (
)B substrates. From the atomically resolved STM images we could determine the shape of the QDs. The quantum “dots” are generally rather flat entities better characterized as “lenses”. In order to achieve this flatness, the QDs are terminated by high-index bounding facets on low-index substrates and vice versa. Our results will be summarized in comparison with the existing literature. 相似文献
Adsorption of Pb2+ ions on the combustion derived nanosized γ-Fe2O3 and its thiourea complex composite is reported. The adsorbents upon adsorption of Pb2+ ions are characterised by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis and infrared spectroscopy techniques. The eluent is characterised by atomic absorption spectroscopy for the estimation of Pb2+ ions. The reduction in the amount of lead after adsorption was estimated to be around 50% in case of complex composite adsorbent and around 15% in case of the γ-Fe2O3 adsorbents. Orthorhombic PbSO4 precipitated out from the eluent and is reported with a model reaction. Adsorption of lead onto the complex composite is explained through the formation of a surface tertiary complex. The advantage of employing a thiourea-γ-Fe2O3 complex composite as solid adsorbent for the adsorption of heavy metal pollutants is envisaged in the present investigation. 相似文献
A novel and convenient route for the synthesis of biologically potent and rare L-hexose derivatives from D-glucose is described. Conversion of diacetone-alpha-D-glucose (14) into 1,2:3,5-di-O-isopropylidene-beta-L-idofuranose (19) was efficiently carried out in two steps. Orthogonal isopropylidene rearrangement of compound 19 led to 1,2:5,6-di-O-isopropylidene-beta-L-idofuranose (27), which underwent regioselective epimerization at the C3 position to give the L-talo- and 3-functionalized L-idofuranosyl derivatives. Hydrolysis of compound 19 under acidic conditions furnished 1,6-anhydro-beta-L-idopyranose (35) in excellent yield, which was successfully transformed into the corresponding L-allo, L-altro, L-gulo, and L-ido derivatives via regioselective benzylation, benzoylation, triflation and nucleophilic substitution as the key steps. Applications of these 1,6-anhydro-beta-L-hexopyranoses as valuable building blocks to the syntheses of 4-methylcoumarin-7-yl-alpha-L-iduronic acid and the disaccharide moieties of bleomycin A(2) as well as heparan sulfate are highlighted. 相似文献
Method for the synthesis of m-and p-isomers of 4-[2-(ethynylphenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxides by the cross-coupling of 4-[2-(3-iodophenyl)vinyl]-and
4-[2-(4-iodophenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxides with (trimethylsilyl)acetylene followed by desilylation
was elaborated. The reactions at the CH-fragment of the ethynyl group were performed. The Mannich reaction proceeds with the
loss of a spin label, whereas the oxidative homocoupling, with its retention.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2051–2054, October, 2007. 相似文献