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91.
G. A. Gavrilova M. G. Voronkov N. N. Chipanina L. I. Gubanova O. M. Trofimova Yu. L. Frolov 《Russian Chemical Bulletin》1995,44(4):667-669
The IR spectra of solutions of (=OSi)-(benzoyloxymethyl)trifluorosilane (1),-(benzoyloxymethyl)methyldifluorosilane (2), and butyl benzoate (3) are examined in the region of thev(C=O) stretching vibrations in 24 solvents. The ability of compounds1—3 to undergo specific intermolecular interactions is evaluated from the dependence ofv(C=O) on the Kamlet-Taft (*,, ) parameters, which was obtained for the carbonyl groups involved in the intramolecular coordinate (=OSi) bond and for free carbonyl groups. The corresponding values of the coefficients in the Kamlet-Taft equations are indicative of a weak ability of pentacoordinate silicon compounds1 and2 to undergo acid-base interactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 689–692, April, 1995. 相似文献
92.
Alternative Ligands. XXII. Rhodium(I) complexes with Donor/Acceptor Ligands of the Typs Me2PCH2CH2SiXnMe3?n(X = F, Cl, OMe) Donor/acceptor ligand of the type Me2PCH2SiXnMe3?n react with [Rh(CO)2Cl]2 ( 1 ) to give the mononuclear complexes RhCl(CO)(PMe2CH2CH2SiXnMe3?n)2 ( 2-6 , Table 1) with planar geometry of the donor atoms, one exception being Me2PCH2CH2CH2SiCl3, yielding the crystalline RhIII-complex RhCl2(CO)(PMe2CH2CH2SiCl2)(PMe2CH2CH2SiCl3) ( 7 ) by oxidative addition of one of the SiCl bonds to the Rh1 precursor. Structures with Rh → Si interaction between the basic central atoms and the acceptor group SiXnMe3?n could be detected in the isolated products neither spectroscopically nor by X-ray diffraction of the two representatives RhCl(CO)(PMe2CH2CH2SiF3)2 ( 2 ) and RhCl(CO)[PMe2CH2CH2siF3]2 ( 2 ) and RhCl(CO) [PMe2CH2CH2Si(OMe3]2 ( 6 ). The presence of such acid/base adducts in the reaction mixture is indicated for the more acidic acceptor groups SiXnMe3?n byvco values near 1990cm?1, (see Table 3). The complex RhCl(CO)PMe3)(PMe2CH2CH2SiF3 ( 8 ) is obtained by the reaction of RhCl(CO)(PMe3)2 ( 9 ) with Me2PCH2SiF3 and has been identified spectroscopically in a mixture with 2 and 9 . 相似文献
93.
94.
为增强有机锗化合物的生物活性,合成了一系列有机锗氨基酸酯类倍半氧化物,并重点研究了它们的快原子轰击质谱(FABMS)。研究结果表明:该系列化合物的各碎片离子峰与其组成及结构均有很好的对应关系及很强的规律性 相似文献
95.
A novel conjugation-elongated bis(ethylenedithio)tetraselenafulvalene (BETS) type donor, 2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene (BEDT-HBDST) and its magnetic and non-magnetic anion salts, (BEDT-HBDST)2MX4 (MX4−=FeCl4−, GaCl4−, FeBr4− and GaBr4−), were prepared. These four salts are isostructural and belong to the space group of P2/c. They showed semiconducting behavior with small activation energies (59-64 meV). The band structures of these salts are quasi one-dimensional and there is a midgap between the upper band and the lower band, since the degree of dimerization is significant in the stacking direction. The MX4− ions are located between the donor columns and near to the ethylenedithio moieties of the donor molecules. The magnetic susceptibilities of the FeCl4− and FeBr4− salts follow the Curie-Weiss law with Curie constants of 4.6 and 4.8 emu K mol−1 (sum of the spins of S=5/2 and S=1/2) and negative Weiss temperatures of θ=−1.2 and −4.9 K, respectively, revealing a weak antiferromagnetic interaction of 3d spins of the FeCl4− and FeBr4− anions. The Fe?Fe (6.66-7.60 Å), Cl?Cl (4.81-4.82 Å) and Br?Br (4.74-4.77 Å) distances in the crystal structures of these salts are significantly long. Therefore, the direct magnetic interaction between the 3d spins of the nearest neighboring Fe3+ ions appears to be not readily accessible. 相似文献
96.
Reduction of ZrBr4 with HSnBu3 yielded a blue solid. When this blue solid was treated with PMe3, a hexanuelear cluster [Zr6Br14H4( PMe3)4] (2) was isolated. Reaction of the blue solid with [PPh4]Br in CH2Cl2 resulted in the formation of a paramagnetic and unstable cluster anion, [Zr6Br18H5]2– (3), which disproportionated to form a new cluster anion, [Zr6Br18H5]3– (4) and some Zr(IV) species. Compounds containing 4 can also be obtained from reaction of the blue solid with Br– in MeCN. Reduction of ZrCl4 with HsnBu3 gave a red–brown solid, and [Zr6Cl14H4(AsMe3)4] (9) and [Zr5Cl12H4(AsMe3)5](8) were obtained by reaction of the red–brown solid with AsMe3. No cluster compounds containing amine ligands were obtained in the reaction of the red–brown solid with amines; only compounds containing the [Zr6Cl18 H5]3– anion and ammonium cations were isolated. Altogether ten products were characterized by single crystal X-ray diffraction and where possible, by 1H NMR studies. 相似文献
97.
State of Molecules and Ions in the Structural Channels of Synthetic Beryl with an Ammonium Impurity 总被引:1,自引:0,他引:1
The contents of the structural channels of beryl, grown hydrothermally from an ammonium-containing solution, were investigated by IR and EPR spectroscopy. Using IR spectroscopy we found that water molecules, ammonium ions, and a small number of HCl molecules enter the structural channels of beryl in the course of mineral growth. In these beryls, the ammonium ions play the role of alkali cations. The ammonium ions are as rigidly fixed in the lattice as are water molecules; they are eliminated by calcination at high temperatures close to the decomposition temperature. On exposure to radiation at 77 K, the paramagnetic NH
3
+
and H0 radicals are stabilized in the structural channels of beryl. In addition to the known H0 radical, other states of atomic hydrogen, interacting with medium protons, are observed as well. For one of the additional radicals, Hb, we suggest the model of atomic hydrogen stabilized at the center of a silicon-oxygen ring with two water molecules in adjacent cavities. 相似文献
98.
CBr_4和CCl_4分子的解离反应前人已做了许多工作,他们分别采用射频放电、电子轰击、He~ 的传能反应等方法研究了CCl_4和CBr_4的解离反应,得到了CCI(A)、CCl~ 、CBr~ 等碎片的发射光谱。有关亚稳态原子与它们的传能反应,只有某些较简单的报道,对传能反应机理也未作深入探讨。本文研究了各种亚稳态原子He(2~3S)、Ne(~3P_(0.2))、Ar(~3P_(0.2))与CCl_4和CBr_4分子的传能反应,并对反应机理进行了初步的讨论和分析。 相似文献
99.
100.
The determination of seven saponins in crude plant extracts by electrospray ionization mass spectrometry (ESI-MS) and fast atom bombardment mass spectrometry (FAB-MS) is described. Distinct protonated and natriated (Na-adduct) molecular ions in ESI-MS spectra readily provide molecular weight information, which can be further verified using clusters of molecular ions. Saponin mixtures can be analyzed by ESIMS on varying the potential difference between the capillary and skimmer in the ESI source to decompose impurities. ESI-MS uses less amount of sample than that required by FAB-MS. ESI-MS does not produce structural information, however. The FAB-MS spectra consist mainly of protonated and deprotonated molecular ions with limited structural information. (-)-FAB-MS is more suitable for analyzing saponin samples than the (+)-FAB-MS. 相似文献