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1.
Gorobinskii L. V. Chernyavskii A. S. Solntsev K. A. Kuznetsov N. T. 《Russian Journal of Coordination Chemistry》2001,27(3):147-149
Reactions of iodination of monosubstituted derivatives of B12H11X2–anion (X = OC(O)CH3, OH, SCN) were studied. The reactions were shown to proceed smoothly to give B12H10(OC(O)CH3)I2–((carboxy)(iodo)[decahydro[I
h1551-20-closo]dodecaborate(2–)] anion), B12H10(OH)I2–((hydroxo)(iodo)[decahydro[I
h1551-20-closo]dodecaborate(2–)] anion), and B12H10(SCN)I2–((thiocyanato)(iodo)[decahydro[I
h1551-20-closo]dodecaborate(2–)] anion) in high yields, irrespective of the solvent used (benzene, H2O–ROH, where R = C2H5, CH2CH2CH3).1 相似文献
2.
Structure, stability, and dissociation of H2BSiN, H2NSiN, H2PSiN and their isomers H2BNSi, H2NNSi, H2PNSi have been studied in detail using ab initio MP2 and CCSD(T) methods. After dissociation of H2BNSi, H2NNSi, H2PNSi and their isomers, the fragmented atoms have been considered to be either in their ground state or in their valence excited state in various dissociation channels. Only allowed dissociations of these molecules are considered. Various dissociation channels of H2BNSi, H2NNSi, H2PNSi and their isomers have been explored and interesting trends are observed for the dissociation of stable isomers H2BNSi, H2NNSi, H2PNSi and less stable isomers H2BSiN, H2NSiN, H2PSiN. The effect of substituents on their structural properties has been discussed. The potential energy surfaces for the RSiN ? RNSi isomerization reactions have been analyzed. The structural properties of these molecules agree well with the theoretical values wherever available. 相似文献
3.
E. A. Il’inchik M. K. Drozdova O. P. Yur’eva K. G. Myakishev V. V. Volkov 《Russian Journal of Inorganic Chemistry》2009,54(12):1866-1871
Triphenylguanidinium Ph3GH+ salts with the anions B10H 10 2? , B12H 12 2? , B9C2H 12 2? , [Co(C2B9H11)2]?, and [Ni(C2B9H11)2]? were synthesized and described by DTA, IR spectroscopy, and solid-state luminescence. By IR spectroscopy, it was shown that intermolecular interactions involving the NH groups of the cation are enhanced in the sequence [Co(C2B9H11)2]? ~ [Ni(C2B9H11)2]? < B9C2H 12 2? < B12H 12 2? < B10H 10 2? . 相似文献
4.
V. K. Kochnev V. V. Avdeeva E. A. Malinina N. T. Kuznetsov 《Russian Journal of Inorganic Chemistry》2013,58(7):793-799
The electronic and geometric structures of different isomers of the closo-B10H12 boron cluster have been calculated by the density functional theory method (in the B3LYP/6-311++G**//B3LYP/6-31G* approximation). The compound is considered to be the diprotonated (H*) analogue of the well-studied B10H 10 2? anion and serves as a model system. The increase in the relative energies of isomers and the preferred location of the extra H* protons near the opposite B(1) and B(10) “poles” are consistent with the charge separation (in the framework of the Mulliken population analysis) between B(1) and B(10). The reactions of migration of one or simultaneously two H* protons in B10H12 over the boron polyhedron have been considered, and the corresponding energies of elementary events E and activation barriers h have been estimated. The elementary events have been predicted in which both H* protons simultaneously move along the trajectories near the opposite B(1) and B(10) poles of the B10H 10 2? polyhedron with the same or opposite changes in the angles determining the H* position with respect to the B(1)–B(10) axis. The activation barrier to the “opposite” migration of the H* protons has been assessed to be h ~ 1.2 kcal/mol, whereas for the migration of the H* protons in the same direction, h ~ 1.4 kcal/mol. The H* proton transfer from the position near the B(1) pole to the position near the opposite B(10) pole is hindered, and higher activation barriers on the order of h ~ 13–15 kcal/mol should be overcome for this transfer to occur. 相似文献
5.
Eiserbeck C Nelson RK Grice K Curiale J Reddy CM Raiteri P 《Journal of chromatography. A》2011,1218(32):5549-5553
18α(H)-, 18β(H)-oleanane and lupane are angiosperm-derived biomarkers that are used as age indicators for the Late Cretaceous onwards when the first proliferation of angiosperms occurred. In addition, the 18α(H)-/18β(H)-oleanane ratio is employed as a thermal maturity parameter of crude oil. However, evidence has shown that accurate quantification of these compounds has been impeded by inadequate chromatographic separation by traditional one-dimensional gas chromatography. In this study, we present the separation of 18α(H)-, 18β(H)-oleanane and lupane with comprehensive two-dimensional gas chromatography (GC×GC). Furthermore, it was observed that 18β(H)-oleanane elutes earlier than 18α(H)-oleanane in second dimension (polarity) which we attribute to steric hindrance effects. Two GC conditions have been developed in order to achieve baseline separation of the triterpenoids of interest in complex mixtures such as sediment extracts and crude oils. 相似文献
6.
Majid M. Heravi Hamideh Alinejhad Fatemeh Derikvand Hossein A. Oskooie Bita Baghernejad Fatemeh F. Bamoharram 《合成通讯》2013,43(14):2033-2039
We report here two simple methods for the synthesis of benzo[c]acridine derivatives from three-component, one-pot condensation of 1-naphthylamine, dimedone, and a variety of substituted aldehydes in the presence of a catalytic amount of NH2SO3H or H6P2W18O62 · 18H2O under solvent-free conditions at 120 °C or in refluxing ethanol. 相似文献
7.
运用MP2/aug-cc-pVDZ对B…HY氢键复合物和B…BrY卤键复合物(B=C4H14,CdH6,Y=F,Cl,Br)的几何构型及相互作用能进行了研究.研究发现对于相同的路易斯碱来说,B…HY和B…BrY的几何构型非常类似,B…BrY卤键键能大于B…HY氢键键能.电子密度拓扑分析表明C4H4(S)…BrY,C4H4(T).…BrF之间的卤键作用介于离子键和共价键之间,其余的氢键和卤键作用均为闭壳层相互作用.形成氢键和卤键后,卤化氢和双卤分子的原子积分性质都发生了变化,B…HY中H原子能量增加,而B…BrY中Br原子能量减少. 相似文献
8.
Majid M. Heravi Tandis Hosseini Fatemeh Derikvand Seyed Yahya S. Beheshtiha Fatemeh F. Bamoharram 《合成通讯》2013,43(16):2402-2406
In this work, a rapid and efficient one-pot method for the synthesis of indeno[1,2-b]quinoline-7-one derivatives by condensation of 1-naphthylamine, 1,3-indanedione, and different aldehydes in the presence of H6P2W18O62·18H2O as a green and reusable catalyst in refluxing acetic acid is described. 相似文献
9.
Nanang Rudianto Ariefta Hasna Tazkia Nikmawahda Takuya Koseki Yoshihito Shiono 《Tetrahedron letters》2019,60(52):151361
Four new polyketides, fusopoltides B–E, were isolated, along with four known compounds, from Fusarium solani B-18 cultured on brown-rice. Fusopoltide B is a diastereomer of its co-isolated known compound, fusopoltide A, featuring a pentaleno[1,2-c]pyran ring system. Fusopoltide C and fusopoltides D–E are incorporated the first natural polyketides featured decahydro-pentaleno[1,2-c]pyran and pentaleno[1,2-c]furan ring systems, respectively. The structural assignments were established using comprehensive spectroscopic techniques, the modified Mosher's ester method, and electronic circular dichroism (ECD) calculations. 相似文献
10.
本文用从头计算方法研究了含32个顶点的硼烷B32H32^0^.^2^-及裸原子簇B32与C2B30的构型,稳定性及反应活性,B32的优化计算结果表明,12个5配位与20个6配位两类硼原子不在同一球面时最稳定,而且所含两种B-B核间距离(R56,R66)的优化值验证了Lipscomb的经验数值,B32,B3232^2^-电子结构及原子布居的计算表明骨架成键轨道满足Wade规则。相应的计算还表明,中性 相似文献
11.
Zusammenfassung B-Chlorborazole reagieren mit Alkalimetallen unter Kondensation. Aus Monochlorborazolderivaten entstehen so B,B-Biborazyle, aus Dichlorborazolen B,B-Polyborazylene und aus Trichlorborazolen vernetzte Polymere von guter thermischer Beständigkeit.Mit 3 AbbildungenHerrn Prof. Dr.F. Halla zum 80. Geburtstag gewidmet. 相似文献
12.
在结构化学的教学中,常常要讨论二硼烷(B2H6)等“缺电子分子”的几何结构和化学键的性质.二硼烷的几何结构已早有定论,因为无论是它的化学性质,还是包括电子衍射、核磁共振、X-射线在内的广泛物理化学研究,都表明两个硼原子与四个端氢原子共平面,另外两个氢原子在平面的上下(如图所示).而且,该分子结构中存在三中心双电子化学键也为大家普遍接受.然而,关于B2H6分子中三中心化学键的解释在教科书中却各持己见,甚至同一本书中有两种不同的观点[1]. 相似文献
13.
The experimental data for the liquid- and gas-phase reactions of atoms and radicals with organoelement compounds R
n – 1E–H
where E = Ge, Sn, P, and Se, are analyzed within the framework of the parabolic model of radical abstraction reactions. The parameters characterizing the activation energies of such reactions involving H, O, and F atoms and
, R
, aryl (A
), R
, and nitroxyl (Am
) radicals are determined. The activation energies for thermally neutral reactions E
e
, 0 are calculated. Reactions of a hydrogen atom with the H–element bond are characterized by the close E
e
, 0 (kJ/mol) values: 51.4 (GeH4), 52.8 (PH3), and 52.6 (SeH2). The E
e
, 0 values for the reactions of alkyl radicals with the Ge–H and Sn–H bonds are also close: E
e
, 0 (kJ/mol) = 62.7 (R"3GeH) and 63.2 (R"3SnH). Low E
e
, 0 values are typical of the reactions of alkoxy radicals (E
e
, 0 (kJ/mol) = 43.9 (GeH4), 46.2 (R"3GeH), 48.9 (R"3SnH), 43.8 (PH3) and oxygen atoms (E
e
, 0 (kJ/mol) = 41.0 (GeH4) and 47.3 (SeH2). Higher E
e
, 0 values are found for the reactions of peroxy radicals (E
e
, 0 (kJ/mol) = 62.8 (R"3GeH) and 60.6 (R"3SnH)) and nitroxyl radicals (E
e
, 0 (kJ/mol) = 81.3 (R"3GeH) and 77.4 (R"3SnH). The atomic radius of element E affects the activation energy of a thermally neutral reaction. The E–H bond dissociation energies for seven germanium and two tin compounds, as well as for five phosphites, are calculated from the kinetic data in terms of the parabolic model. 相似文献
14.
Szolnoki E Hetényi A Martinek TA Szakonyi Z Fülöp F 《Organic & biomolecular chemistry》2012,10(2):255-259
Various patterns of foldameric oligomers formed by trans-ABHC ((1S,2S,3S,5S)-2-amino-6,6-dimethylbicyclo[3.3.1]heptane-3-carboxylic acid) and β(3)-hSer residues were studied. NMR, ECD and molecular modelling demonstrated that octameric and nonameric sequences with multiple i-i+3 ABHC pair repulsions attain the β-H18 helix in CD(3)OH. As a close relative of the α-helix, this helix type is stabilized by i-i+4 backbone H-bond interactions. The formation of the β-H18 helix was found to be solvent- and concentration-dependent. Upon dilution, the β-H18 → β-H12 helix transition was revealed by concentration-dependent ECD, DOSY-NMR and TEM measurements. 相似文献
15.
《Polyhedron》1986,5(10):1639-1643
2-D 11B-11B correlation (COSY) spectra have been obtained on the series of monosubstituted and disubstituted octahydrotriborate anions, [B3H7(X)]− (X = Cl, NCS, NCSe, NCBH3, NCBH2Cl, NCBPh3, NCBH2CN, NCB3H7 or CNB3H6Cl) and [B3H6(Cl)(X)]− (X = Cl, NCS, NCBH2Cl or NCB3H7). All monosubstituted derivatives and [B3H6(Cl)2]− showed a coupling correlation between the substituted and unsubstituted borons. The unsymmetrically disubstituted derivatives showed only one coupling correlation, between the borons carrying the substituents. The absence of other correlations is attributed to relaxation phenomena. The correlations are independent of the solid-state structural type. 相似文献
16.
《Chemical physics》1987,118(3):457-466
The gas-phase clustering reactions Cl− (ROH)n−1 + ROH ⇄ Cl− (ROH)n with n ⩽ 11 for ROH = H2O, CH3OH, C2H5OH, i-C3H7OH, n-C3H7OH, and t-C4H9OH were measured using a high-pressure mass spectrometer. It seems likely that for CH3OH and C2H5OH, six ligands complete the shell structure and that ligands with n ⩾ 7 belong to the outer shell. The bond energies D(ROH---Cl−) increase in the order H2O < CH3OH < C2H5OH < i-C3H7OH < t-C4H9OH < n-C3H7OH. The observed strong bond of n-C3H7OH---Cl− may be due to the fact that both the acidic hydrogen atoms in the −OH and terminal −CH3 of n-C3H7OH interact with Cl− with the most favorable configuration. For Cl− switching reactions, Cl− (H2O)n + (ROH)n ⇄ Cl− (ROH)n + (H2O)n, the ΔG0n values converge to the values of free energies of transfer of Cl− from water to ROH solvent ( = ΔG0n with n → ∞) with n ≈ 7. The observed convergence of ΔG0n is due to compensation of changes in enthalpy and entropy, i.e. both ΔH0n and TΔS0n show increasing divergence from the values of enthalpies and entropies of transfer of Cl− from water to ROH solvent, respectively, with n = 1 → 7. This is due to the stronger interactions of ROH with Cl− than that of H2O in the inner shell of Cl− (ROH)n at the expense of the less favorable entropy changes (less freedom of motion for ligands in the inner shell). 相似文献
17.
LIN Chen-Sheng LI Jun LIU Chun-WanFujian Institute of Research on the Structure of Matter Chinese Academy of Sciences State Key Laboratory of Structural Chemistry Fuzhou Fujian China 《中国化学》1994,12(4):305-313
The molecular orbitals for B4H4, B4F4, B4Cl4, B4Br4 and B4I4 have been calculated by using all-electron or effective core potential ab initio method at the self-consistent field level using basis sets with diffuse and polarization functions. The boron-boron and boron-halide (-hydrogen) distances of these cage compounds are optimized with three kinds of basis sets constrained to a tetrahedral symmetry. According to the localization scheme of Boys, four three-centered two-electron (3c2e) B-B-B bonds localized on each of the faces of the B4 tetrahedron are derived for B4X4 clusters. The HOMO-LUMO energy gaps, atomization energies and Mulliken overlap populations of these compounds indicate that the stabilities of the clusters decrease in the sequence of B4F4 > B4Cl4, B4H4 > B4Br4 > B4I4. 相似文献
18.
Mark A. Fox Carlo Nervi Antonella Crivello Andrei S. Batsanov Judith A. K. Howard Kenneth Wade Paul J. Low 《Journal of Solid State Electrochemistry》2009,13(10):1483-1495
The influence of aryl ring substituents X (F, OMe, NMe2, NH2, OH and O−) on the physical and electronic structure of the ortho-carborane cage in a series of C,C′-diaryl-ortho-carboranes, 1-(4-XC6H4)-2-Ph-1,2-C2B10H10 has been investigated by crystallographic, spectroscopic [nuclear magnetic resonance (NMR), UV–vis], electrochemical and
computational methods. The cage C1–C2 bond lengths in this carborane series show small variations with the electron-donating
strength of the substituent X, but there is no evidence of a fully evolved quinoid form within the aryl substituents in the
ground state. In the 11B and 13C NMR spectra, the ‘antipodal’ shift at B12, and the C1 shift correlates with the Hammett σ
p value of the substituent X. The UV–visible absorption spectra of the cluster compounds show marked differences when compared
with the spectra of the analogous substituted benzenes. These spectroscopic differences are attributed to variation in contributions
from the cage orbitals to the unoccupied/virtual orbitals involved in the transitions responsible for the observed absorption
bands. Electrochemical studies (cyclic and square-wave voltammetry) carried out on the diarylcarborane series reveal that
one-electron reduction takes place at the cage in every case with the voltage required for reduction of the cage influenced
by the electron-donating strength of the substituent X, affording a series of carborane radicals with formal [2n + 3] electron
counts.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Z. Slanina 《Journal of Radioanalytical and Nuclear Chemistry》1991,153(6):439-449
Using 8 modifications of recently developed flexible water potentials, zeropoint energy differences between the isomeric water-dimer isotopomers differing in the hydrogen isotope involved in the hydrogen bond have been evaluated. In all the 18 possible pairs, the species bound through the heavier isotope is always lower in the energy term.Dedicated to the memory of the late Dr. Mojmír Tomáek (1931–1990).Part LVII in the series Multi-Molecular Clusters and Their Isomerism, Part LVI — see Ref. 42; for a wider perspective of the water-dimer isotopomeric isomerism — see43Part XXXVI. 相似文献
20.
《Fluid Phase Equilibria》1999,165(2):157-168
A simple method is developed to estimate mixture critical temperatures (Tc), pressures (Pc), and densities (ρc) as a function of overall composition (X) from near critical region experimental coexistence data. This three-step method is applied to four mixtures, CO2–C3H8, CO2–nC4H10, C2H6–C3H8, and C3H8–nC4H10. Isothermal liquid–vapor coexistence data, which includes temperature, vapor pressure, coexisting densities (ρℓ and ρv), and coexisting compositions for the more volatile component (x1v and x1ℓ) are used. In the first step, the difference of the saturated liquid and vapor densities (ρℓ−ρv) is fitted to an empirical function in ((Pc−P)/Pc) to obtain Pc. Then P/Pc and ((ρℓ+ρv)/2ρc) are simultaneously fitted to functions of a polynomial in (X1−(x1v+x1ℓ)/2) yielding estimates of ρc and X1. Finally, the discrete estimated critical data points are fitted with an equation to provide a continuous representation of the critical lines. The method is successfully tested for the mixtures, CO2–C3H8 and CO2–nC4H10, for which there is a reasonable amount of isothermal data. The procedure is then applied to the mixtures, C2H6–C3H8 and C3H8–nC4H10, for which there are sparse data. For all four mixtures, the critical temperature line, Tc vs. X1, matches literature values within ±0.5%. The critical pressure line, Pc vs. X1, and critical density line, ρc vs. X1, match literature values, in general, within ±2%. 相似文献