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Marie-Thérèse Youinou Jacques-Emile Guerchais G. Sturtz 《Journal of Molecular Structure》1973,18(1):109-121
Infrared and nuclear magnetic resonance spectroscopy data are presented for a series of complexes [ZnXL], where L? denotes the {(C2H5O)2POCHCOCH2NR2}? anion with R = CH3 (La?) or C2H5 (Lb?) and X a halogen or pseudohalogen. The infrared data reveal that the splitting of the absorption v(P → O) depends on the nature of X? and is interpreted in terms of a crystal effect. The following order Cl? < NCO? ~ Br? < I? < NCS? < NCSe? is consistent with the ligand size. Nonequivalent protons on a given methylene group and nonequivalent methyl or ethyl groups bonded to nitrogen are detected by NMR spectroscopy of deuterochloroform solutions of these complexes. With La?, the rate of exchange increases in the order NCO?, Cl?, Br?, X? (X? = I?, NCS?, NCSe?). The kinetic parameters for exchange of nonequivalent N(CH3)2 groups were determined. 相似文献
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Francis Garnier Pierre Krausz Jacques-Emile Dubois 《Journal of organometallic chemistry》1979,170(2):195-201
The photoinduced metathesis [W(CO)6CCl4hν] of cis- and trans-RCH=CHMe gives 2-butene in a very high trans but low cis stereoselectivity. Propene behaves like a cis olefin. These results are consistent with the proposal of a dinuclear tungsten intermediate, which requires high steric constraints in the transalkylidenation step. 相似文献
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Reactivities of homogeneous series of ethylenic compounds R1CHCH21, trans R1CHCHMe 2, R1MeCCH23 and R1CHCMe24 have been measured in methanol at 25°C (R1 Me, Et, n-Pr, -CH2C6H5-CH2OCOCH3, -CH2Cl). The criterion developed to decide between a bridged and a carbonium ion-like transition state is based on an internal comparison of the series and avoids resorting to external structural scales. Even in the case of alkenes 3 and 4 which are very dissymmetric with respect to polarity, the sensitivity to polar effects remains constant and the transition state behaves like a symmetric entity; only a slight secondary effect, attributed to hyperconjugation, is detectable. 相似文献
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Jacques-Emile Dubois Georges Axiotis Emmanuel Bertounesque 《Tetrahedron letters》1985,26(36):4371-4372
The proposed cross aldolization of α-bromoketones with aldehydes in presence of Chromium (II) chloride is an excellent stereospecific reaction. One exception to the stereospecific orientation is reported. 相似文献
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The formation of transannular products in the bromination of cis-cyclooctane by NBA in MeOH is taken as direct evidence for the existence of a carbonium ion intermediate. 相似文献
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