共查询到20条相似文献,搜索用时 2 毫秒
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C. Lecomte Y. Dusausoy J. Protas J. Tirouflet A. Dormond 《Journal of organometallic chemistry》1974,73(1):67-76
The crystalline structure of the racemic form m.p. 164° C of the compound (h5 -3-MeC5H3C(Me2)C6H5)(h5-C5H5)Ti (2,6-Me2C6H3O)Cl has been determined by X-ray diffraction to establish the relative configuration of the two chiral moieties. This compound may be used further as a reference for studies on dynamic stereochemistry around the titanium atom. A systematic absolute nomenclature is proposed for this type of structure. 相似文献
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The first example of transfer of axial chirality into central chirality during a reaction of hetero-ene synthesis performed with optically active γ-allenic aldehyde is reported. 相似文献
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The complexes (C6H5X)Cr(CO)3, where X is COCH3, CH2,CO2CH3 and CH3 are readily alkylated by either sodium hydride in DMF or by potassium tert-butoxide in DMSO. The activating influence brought about by the electron-withdrawing effect of the Cr(CO)3 group can be modified by replacement of a carbonyl group by P(OPh)3 or CS which lead to mono or dialkylated products respectively. 相似文献
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Oleg I. Kolodiazhnyi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):39-42
Abstract The first stable heterocumulenes with dicoordinated phosphorus were obtained. The chemical properties of the new heterocumulenes are discussed. 相似文献
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《Journal of Molecular Catalysis #》1981,10(3):377-384
Iridium pyridino phosphino complexes extremely active in olefin hydrogenation catalysis, were anchored on highly crosslinked polystyrene—divinyl-benzene macroporous resins carrying well dispersed phosphine groups. Although the catalytic sites are totally dispersed, the catalysts are more or less rapidly deactivated. An alternative cause of deactivation might be a dissociation process followed by dimerization of the dissociated complex. 相似文献
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Oleg I. Kolodiazhnyi 《Tetrahedron letters》1982,23(47):4933-4936
The first stable heterocumulene with dicoordinated phosphorus t-BuP=C=NBu-t was obtained from t-BuP(SiMe3)NBu-t. The I.R. and Mass Spectrum as well as the NMR (1H, 13C, 31P) data are discussed. The chemical properties of the new heterocumulene are also described. 相似文献
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A magnetooptical study of some halogenotertiobutylphosphines is performed in order to improve the so-called regular relationship which seemed to exist between the magnetic rotation, ?dP, of the lone pair and the bond angles in PX3 compounds. It is clearly shown that, in any case, ?dP is largely lower than the extreme value which was observed in PX3 molecules for which XPX=100°. Thus, the existence of the previously invoked relationship vanishes and the question remains as to why there exists a maximum of ?dP for XPX of 100°. 相似文献
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The photochemical addition of nitrenes to isonitriles leads to carbodiimides or/and ureas. The application of this reaction to 1-isocyano sugars offers an approach to the synthesis of glycosylbarbiturates. 相似文献
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We studied the electrical conductivity σ and the glass transition temperature Tg of an epoxy resin filled with a carbon black. It could be shown that σ and Tg depend on the volume concentration of carbon black and that the concentration dependence of Tg is sensitive to the thermal conditions of polymerization. 相似文献
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Derivatives of a new diaminotrideoxy-d-ribo-hexopyranose, a component of the antibiotic tobramycin, have been prepared by addition of the elements of hydrazoic acid to the α, β-unsaturated ketone 8. After 5 min only the kinetically favored product 13 was observed, which is gradually transformed into the thermodynamically more-stable substance 20. The equilibrium mixture after 5 hours contained d-erythro and d-threo isomers 20 and 13 in the ratio 6:4 The d-erythro azide 20 was converted into the derivatives of di-N-acetyl tobrosamine. 相似文献
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M. Sarrazin M. Bourdeaux-Pontier C. Briand E.-J. Vincent 《Magnetic resonance in chemistry : MRC》1975,7(2):89-93
The NMR spectra of five benzodiazepinones are determined over a range of temperature. They indicate that the seven ring has a twist-boat shape, which inverts more or less rapidly according to the nature of substituents. The activation parameters and the rates of inversion are determined and the substituent effects are discussed. 相似文献
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Dissymmetrical vanadocenes CpCp′V are prepared by reduction of the corresponding dichlorides CnCp′VCl2 (Cp = C5H5 ; (Cp′ = C5H4R). Like vanadocene they display a carbeno? behavior and can be coordinated to CS2 and acetylenic compounds. The addition of dissymmetrical acetylenes involve the formation of a chiral center at vanadium. This chirality is detected by partial chromatographic separation of diastereoisomers CpCp″V* (RCCR*) which bear a second chiral center on acetylenic ligand. 相似文献