Home About us Contact
|
Home About us Contact | ||
|
|
||
X-ray Analysis. (x-ray + analysis)
Selected AbstractsNovel Enantioselective Synthesis of Functionalized Pyridylarsanes by a Chiral Palladium Template Promoted Asymmetric Hydroarsanation ReactionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2009Fengli Liu Abstract The asymmetric hydroarsanation reactions between diphenylarsane and (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone and (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate have been achieved by use of the organopalladium complex containing ortho -metalated (R)-[1-(dimethylamino)ethyl]naphthalene as the chiral reaction template in high regio- and stereoselectivities under mild conditions. Hydroarsanation of (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone with diphenylarsane generated two stereoisomeric products in the ratio of 3:1 as five-membered As,N bidentate chelates on the chiral naphthylamine palladium template. Using the same chiral metal template, the corresponding hydroarsanation reaction with (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate gave only one product as a six-membered As,N bidentate chelate. The naphthylamine auxiliary could be removed chemoselectively by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complexes. Subsequent ligands displacement from the palladium using aqueous potassium cyanide generated the optically pure keto- and ester-functionalized chiral pyridylarsane ligands. The absolute configuration and the coordination properties of the pyridylarsanes have been established by single-crystal X-ray analysis.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Single-Electron-Transfer Reactions of ,-Diimine dpp-BIAN and Its Magnesium Complex (dpp-BIAN)2,Mg2+(THF)3EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2006Igor L. Fedushkin Abstract The reactions of (dpp-BIAN)Mg(THF)3 (1) {dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene} with ethyl halides EtX (X = Cl, Br, I) in hexane proceed by single-electron transfer (SET) from the metal complex to the organic halide. Complexes [(dpp-BIAN)(Et)]MgX(THF)n [X = Cl, n = 0 (2); X = Br, n = 2 (3); X = I, n = 1 (4)] are the products of ethyl transfer to an imine carbon atom of a coordinated diimine ligand. The compound [(dpp-BIAN)(Et)]MgBr (3a) was obtained from the reaction of free dpp-BIAN with ethylmagnesiumbromide in hexane. In this case SET from the Grignard reagent to the neutral diimine takes place. Compounds 2,4 and 3a were isolated as crystals and characterized by 1H NMR spectroscopy. The molecular structure of 3 was determined by single-crystal X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Lithium and Potassium Amides of Sterically Demanding AminopyridinesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2004Natalie M. Scott Abstract The reaction of Grignard compounds of 1-bromo-2,4,6-diisopropylbenzene (1) or 1-bromo-2,6-dimethylbenzene (2), formed in situ, with 2,6-dibromopyridine in the presence of a catalytic amount of [(dme)NiBr2] (dme = 1,2-dimethoxyethane) and tricyclohexylphosphane (1:2 ratio) leads to the corresponding monoarylated bromopyridines. These bromopyridines undergo Pd-catalysed aryl amination (Buchwald,Hartwig amination) with 2,6-diisopropylaniline giving rise to (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine (Ap*H) and (2,6-diisopropylphenyl)[6-(2,6-dimethylphenyl)pyridin-2-yl]amine (Ap,H) (Ap = aminopyridinate). Deprotonation of Ap*H in diethyl ether using BuLi results (after workup in hexane) in a colourless crystalline material. X-ray structural analysis reveals it to be a monomeric three-coordinate lithium aminopyridinate. In toluene solution, an equilibrium between [(Ap*Li)2] (in excess at room temperature) and [Ap*Li(OEt2)] (prominent at low temperature) is observed. Reaction of Ap,H with BuLi in diethyl ether gives rise to [Ap*LiAp*Li(OEt2)]. Deprotonation of Ap*H and Ap,H using KH leads to [Ap*K]n and [Ap,K],, respectively. [Ap,K], is a rare example of a crystalline organometallic polymer, as determined by X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and Monitoring of ,-Bi2Mo3O12 Catalyst Formation using Thermo-Raman SpectroscopyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2004Anil Ghule Abstract Thermo-Raman spectroscopy was used to monitor the dehydration and phase transformations of Bi2Mo3O12·5H2O. The hydrated forms Bi2Mo3O12·5H2O, Bi2Mo3O12·4.75H2O, Bi2Mo3O12·3H2O, Bi2Mo3O12·2H2O, and anhydrous Bi2Mo3O12 were observed during dehydration in the wavelength range from 200 to 1400 cm,1. Representative Raman spectra of these compounds are reported for the first time. The thermo-Raman intensity thermogram showed a systematic dehydration in four steps, and the differential thermo-Raman intensity thermogram confirmed this. Thermogravimetry, differential thermogravimetry, and differential scanning calorimetry results were in harmony with the results of the thermo-Raman spectroscopy. Additionally, the dehydration resulting in formation of anhydrous Bi2Mo3O12 (amorphous Bi2Mo3O12 phase) and the final transformation into the ,-Bi2Mo3O12 phase was observed to be a dynamic thermal process. The slow, controlled heating rate produced ,-Bi2Mo3O12 catalyst with a particle size averaging 200 nm. The catalyst formed was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, time of flight SIMS, transmission electron microscopy, and energy-dispersive X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis, Structures and Reactions of Novel 9,10-Dihydro-9,10-distannaanthracenesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2004Masaichi Saito Abstract A method for the synthesis of 9,10-dihydro-9,10-distannaanthracenes has been improved and applied to the synthesis of novel unsymmetrical 9,10-dihydro-9,10-distannaanthracenes. The first 9,9,10,10-tetrahalo-9,10-dihydro-9,10-distannaanthracenes were successfully synthesized by halogenation of 9,9,10,10-tetrakis(p -methoxyphenyl)-9,10-dihydro-9,10-distannaanthracene. The structures of the newly obtained 9,10-dihydro-9,10-distannaanthracenes were determined by X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and Structure of Two New High Nuclearity Ru/Pt Mixed-Metal ClustersEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2003Brian F. G. Johnson Abstract The reaction of the dianion [Ru5C(CO)14]2, with [PtCl2(MeCN)2] in the presence of silica yields [Ru5PtC(CO)16] (1) and the new compound [PPN]2[Ru10Pt2C2(CO)28] (2), while, in a related reaction, [Ru6C(CO)16]2, undergoes addition of [PtCl2(MeCN)2] to yield the cluster [Ru12PtC2(CO)32(MeCN)2] (3). The high nuclearity compounds 2 and 3 have been fully characterized and their structures determined by single crystal X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Diastereoselective Synthesis of Heteroaromatic Glycine DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2008Trygve Andreassen Abstract A TMSOTf promoted addition of an N - tert -butanesulfinyl ,-imino ester to five-membered aromatic heterocycles furnishes optically active heteroaromatic glycine derivatives with moderate-to-good yield in diastereomeric ratios up to 99,%. The absolute configuration of two of the addition products were solved by X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Utility of Azolium Triflates as Promoters for the Condensation of a Nucleoside Phosphoramidite and a Nucleoside in the Agrawal's Stereoselective Synthesis of Nucleoside Phosphorothioates,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2005Mamoru Hyodo Abstract This paper demonstrates that some azolium triflates, such as N -phenylimidazolium triflate, benzimidazolium triflate and N -methylbenzimidazolium triflate, are more useful than 1H -tetrazole as promoters for the stereoselective condensation of a 5,- O -free nucleoside and a stereochemically pure 5,- O -(p,p,-dimethoxytrityl)-3,- O -{(4R)-1H,3H -pyrrolo[1,2- c]-1,3,2-oxazaphospholidin}-2-yl 2,-deoxyribonucleoside (Rc- 1) or 5,- O -(p,p,-dimethoxytrityl)-3,- O -{(4S)-1H,3H -pyrrolo[1,2- c]-1,3,2-oxazaphospholidin}-2-yl 2,-deoxyribonucleoside (Sc- 2) (Agrawal strategy). The azolium triflates allowed the stereoselective formation of an internucleotide phosphorothioate bond via the above-described condensation using a stereochemically pure phosphoramidite, followed by sulfurization using bis[3-triethoxysilylpropyl]tetrasulfide. The highest diastereoexcess values of the products in the synthesis of dideoxyribonucleoside phosphorothioates using a suitable azolium triflate such as benzimidazolium triflate, N -methylbenzimidazolium triflate or N -phenylimidazolium triflate were 90,96,% in solution phase or 80,88,% in solid phase; these values were higher than those obtained in the synthesis using 1H -tetrazole as a promoter for the condensation of a nucleoside phosphoramidite and a nucleoside. This paper also describes that studies on the absolute configurations of stereogenic phosphorus atoms in the phosphoramidites Rc- 1 and Sc- 2 by meansof two different existing methods, i.,e., the Beaucage method, gave contrary conclusions, and thus the configurations should be determined by an absolutely reliable method, such as X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Water-repellent finishing of cotton fabrics by ultraviolet curingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008F. Ferrero Abstract Cotton fabrics were water-repellent-finished by radical ultraviolet curing of silicone and urethane acrylates with different formulations. The fabrics were impregnated with undiluted resins and with toluene solutions or water emulsions. Moreover, cationic ultraviolet-curable systems were also investigated, such as an epoxy-functional polysiloxane and mixtures of an epoxy resin with hydroxyl-containing silicone additives. The gel content and polymerization yield were considered for the ultraviolet-curing process evaluation. Water-resistance properties were determined in terms of the contact angle, wettability, moisture adsorption, and water vapor permeability measurements, whereas the morphology and surface composition of treated fabrics were examined with scanning electron microscopy and energy-dispersive X-ray analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] | ||||||||||