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81.
Trialkyltin and trialkyllead amides react directly and remarkably easily with 1,3,5,7-tetranitrocubane to form mono- to tetrakis(trialkyltin)- and -(trialkyllead) tetranitrocubanes. These are all stable compounds. The X-ray crystallographic properties of some are given. The (trialkylstannyl)cubanes react with electrophiles such as bromine with unexpected cleavage of alkyltin bonds rather than cubyl-tin bonds. On the other hand, the (trialkylplumbyl)cubanes do ultimately undergo cubyl-lead bond cleavage. This provides a useful way to achieve substitution on the cubane nucleus and provides access to compounds such as 1,3,5,7-tetrabromo-2,4,6,8-tetranitrocubane. The lead derivatives of tetranitrocubane are also useful for making 1,2,3,5,7-pentanitrocubane and 1,2,3,4,5,7-hexanitrocubane. 相似文献
82.
O. E. Nasakin V. V. Pavlov A. N. Lyshchikov P. M. Lukin V. N. Khrustalev M. Yu. Antipin 《Chemistry of Heterocyclic Compounds》1997,33(11):1272-1275
A scheme for the unusually ready selective hydrolysis of three of the cyano groups in 1,1,2,2-tetracyanoethane to 2-cyanoethane-1,1,2-tricarboxamide
by the action of pyruvic acid was proposed. Only one cyano group undergoes hydrolysis in the reaction with sodium pyruvate.
In the course of this reaction, 2-amino-5-methyl-3, 4-dicyano-4,5-dihydrofuran-4,5-dicarboximide, the structure of which was
determined by x-ray diffraction investigation of the monocrystal, is formed.
I. N. Ul'yanov Chuvashsk State University, Cheboksary 428015. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.
11, pp. 1472–1476, November, 1997. 相似文献
83.
Strokach Yu. P. Valova T. M. Barachevsky V. A. Alfimov M. V. Gromov S. P. Vedernikov A. I. Demina O. V. Lukin A. Yu. Shevyakov S. V. Shvets V. I. Khodonov A. A. Lugtenburg J. 《Russian Chemical Bulletin》2003,52(12):2656-2660
Complexation of crown ether vinylogs containing different terminal polar groups with alkali and alkali-earth metal ions in solutions was studied by spectrophotometry. The hypsochromic shift of absorption band maxima in the UV-Vis absorption spectra indicates that the ligands containing the monobenzocrown ether fragments interact with metal ions. The scheme of complexation was proposed, and the stability constants of the complexes were determined. The efficiency of complexation depends on the metal cation size and the structure of the ionophoric fragment. 相似文献
84.
A method allowing for an unprecedented controllable functionalization of oligoamines via N,N-bis-sulfonylation with various sulfonyl chlorides has been developed. Depending on the nature of the sufonyl chloride and reaction conditions such as base, time of reaction, and temperature, each amino group can be selectively mono- or bis-sufonylated. The procedure was investigated in detail with the model substance tris(2-aminoethyl)amine and applied for the preparation of dumbbell-shaped coupled dendrons and second-generation sulfonimide-decorated dendrimers. 相似文献
85.
86.
O. G. Khvostenko V. G. Lukin E. E. Tseplin 《Rapid communications in mass spectrometry : RCM》2012,26(21):2535-2547
The problem under investigation here is establishment of mechanisms of the resonant electron capture by molecules, using the example of duroquinone (2,3,5,6‐tetramethyl‐1,4‐benzoquinone). A solution is important because it will provide new insights into the fundamental physical laws and widespread applications in various fields like molecular nanoelectronics, touched upon herein too. Resonant electron capture (REC) in duroquinone was studied with negative ion mass spectrometry of the REC as the main method, and UV absorption and the photoelectron spectroscopy as the auxiliary ones. The latter were used to study the electronic structures of the various neutral molecular states that are the parent ones for the negative molecular ions formed by electron attachment to the molecules. B3LYP/6‐311 + G(d,p) calculations were widely used throughout the study. As a result, an intensive peak of the negative molecular ions with anomalously high lifetime (200 microseconds) was registered at the attached electron energy of 1.8 eV. The ions were determined to be quartets delaying the electron autodetachment because of spin prohibition and appearing via inter‐system crossing from the negative molecular ion doublets produced in the core‐excited Feshbach resonances. Finally, the pattern of the REC in duroquinone was obtained for the energy region of 1–4 eV which is presented by shape resonances, core‐excited Feshbach resonances and by mechanisms little‐known for molecules of inter‐shell resonances and the formation of ion quartets. The latter were proposed to be related to the negative differential resistance in molecular nanoelectronics. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
87.
88.
V. P. Lukin 《Optics and Spectroscopy》2001,91(6):951-959
Problems of construction of an up-to-date ground-based adaptive telescope equipped with an additional optical system for the formation of a laser reference star are studied. The systems proposed for laser reference star formation allow information on the wavefront tilt to be obtained. 相似文献
89.
Russian Physics Journal - The characteristics of turbulence over mountainous terrain are investigated with an aim to predict propagation of short-wavelength electromagnetic waves (including optical... 相似文献
90.