H2O, H2S与双卤分子间相互作用的电子密度拓扑研究

运用量子化学微扰理论MP2和密度泛函B3LYP方法, 采用6-311＋＋G(d,p)基组, 对H₂O, H₂S与双卤分子XY (XY＝F₂, Cl₂, Br₂, ClF, BrF, BrCl)形成的卤键复合物进行构型全优化, 并计算得到了这些体系的分子间相互作用能. 利用电子密度拓扑分析方法对卤键复合物的拓扑性质进行了分析研究, 探讨了该类分子间卤键的作用本质. 结果表明, 形成卤键后, 作为电子受体的双卤分子X—Y键长增长, 振动频率减小. 复合物体系中的卤键介于共价键与离子键之间, 偏于静电作用成分为主.     

Molecular beam chemiluminescence. Three-body processes in the micro-torr region: The Ba + X2(Cl2, Br2, I2) → BaX*2 reactions

The intensity of the chemiluminescence continua from the title reactions was measured in crossed effusive molecular beams as a function of halogen beam flux. The dominant quadratic pressure dependence of the Ba + Cl₂, Br₂, I₂ reactions at halogen densities as low as ≈ 10¹¹ molecules/cm³ indicates a three-body process (rapid collissional stabilization of a very long-lived collision complex) as the major mode of MX^*₂ formation, while a two-body process is discernible at the lowest X₂ gas densities. The mechanism is discussed in some detail.     

Synthesis and crystal structure of [CODRh(SC6F5)]2

The metathetical reaction of Pb(SC₆F₅)₂ with the halogen bridged compounds [L RhCl]₂ where L are chelating dienes, afforded the chalcogen bridged analogs. Subsequent reactions with a variety of ligands including phosphines, arsines, sulfides and selenides, have shown important differences between sulphur and halogen bridged complexes, attributable to the fluorinated moiety. Some of these reactions will be discussed and the crystal structure of [COD Rh(SC₆F₅)]₂ will be described.     

X-ray study of Hg2Cl2Br2 and HgCl2HgBr2 reactions in solid state

The reactions (I) Hg₂Cl₂(s) + Br₂(g) and (II) HgCl₂(s) + HgBr₂(s) have been investigated by an X-ray method. Both the reactions yield two forms of the mixed halide HgClBr, designated as α-HgClBr and β-HgClBr. The cell parameters of the two are as follows:α-HgClBr: $\text{a = 6.196}\text{A}\text{?}$, $\text{b = 13.12}\text{A}\text{?}$, $\text{c = 4.37}\text{A}\text{?}$, z = 4, ? = 5.91 g/cm³. The powder pattern and cell parameters are similar to that of HgCl₂. Therefore it is probable that the chlorine atoms, in the linear halogenHghalogen molecules of HgCl₂ structure have been replaced by bromines, and since the radius of the bromine atom is larger than that of chlorine, the lattice is larger in this case.β-HgClBr: $\text{a = 6.78}\text{A}\text{?}$, $\text{b = 13.175}\text{A}\text{?}$, $\text{c = 4.17}\text{A}\text{?}$, z = 4, ? = 5.40. These parameters are the same as those reported in the literature for β-Hg(ClBr)₂, and its X-ray powder pattern is similar to HgCl₂. Therefore this phase also has linear halogenHghalogen molecules but the distribution of Cl and Br atoms is perhaps random.Heating the products (I) and (II) up to the melting point increases the amount of α phase and decreases the β phase, whereas crystallization increases the β phase. DTA study has supported the X-ray findings.     

ESR spectra and structure of the (CH3)2AlX− (X = Cl,Br, I) radical anions

After exposure to γ rays at 77 K. (CH₃)₂AlX (X = Cl, Br,or I) in solid solutions of tetramethylsilane gave six-line ESR spectra with a large hyperfine coupling characteristic of ²⁷Al and an additional halogen splitting. The results indicate the formation of (CH₃)₂A1X^? with pyramidal structure. The unpaired electron occupies a π^* orbital composed largely of 3s and 3p Al orbiials and slightly of halogen orbitals.     

Attractive halogen–halogen interactions: F3CCl⋯FH and F3CCl⋯FCH3 dimers

The F₃CCl?FH and F₃CCl?FCH₃ dimers, which feature the halogen–halogen contacts, are investigated at MP2/6–311++G(d,p) and MP2/aug–cc–pVDZ levels of approximation. The binding energies of these complexes are found to be comparable to those of the weak hydrogen bonds. In both complexes the Cl?F are found to be significantly shorter than the sum of the corresponding van der Waals radii. The C–Cl?F contacts are also found to exhibit certain deviation from linearity. However, the energy differences between linear and bent structures are very small and primarily accounted for by electrostatic interactions between remote parts of the dimer. This indicates a high conformational flexibility of the halogen–halogen contacts and may help to explain the diversity of structural features in crystals formed by halogen-containing molecules. In both dimers the halogen–halogen interaction leads to certain shortening of the C–Cl electron accepting bond. This is accompanied by a small increase of the C–Cl stretching frequency. Hence, the two investigated dimers can possibly be classified as the blue-shifting halogen–halogen contacts.     

35Cl NQR in N3P3Cl4Ph2 and N3P3Cl4(NMe2)2

³⁵Cl NQR has been investigated in two cyclotriphosphazene derivatives N₃P₃Cl₄Ph₂ and N₃P₃Cl₄(NMe₂)₂. The observed frequencies are assigned to the various chlorines and the temperature variation of the NQR frequencies studied in the range from 77 K to 300 K. The results are analysed using the Bayer-Kushida-Brown approach. Torsional (librational) frequencies are found to fall in the range 10–25 cm^?1 and are found to be only slightly temperature dependent.     

Beam-gas chemiluminescent reactions of Cu(2D) with Cl2, Br2, and I2

Chemiluminescent reactions involving copper and halogen molecules are shown to result from the bimolecular reaction of metastable Cu(²D) with Cl₂, Br₂, and I₂ under single-collision conditions. The collision-energy dependence of the reactions is described by a hard-sphere model with zero threshold energy. Cross sections for these reactions are compared with that for chemiluminescent reaction of Cu(²S) with F₂.     

29Si and 13C NMR spectra of chloro- and fluoro-substituted linear permethylpolysilanes

²⁹Si and ¹³C NMR spectra are reported for the three halopolysilane series Me(SiMe₂)_nCl, Cl(SiMe₂)_nCl and F(SiMe₂)_nF, where n = 2 to 6. Except for the dihalodisilanes (XSiMe₂)₂, data for all of the compounds fit linear relationships based on substituent constants for chlorine or fluorine atoms in the α, β and γ positions. The effects of halogen substitution on ²⁹Si and ¹³C chemical shifts are rapidly attenuated along the polysilane chain, becoming negligible four atoms away from the halogen. The NMR data provide no evidence for long-range electronic transmission from chlorine or fluorine in halopermethylpolysilanes of the type suggested by other workers [1].     

35Cl, 81Br and 127I NQR spectra of cyclopentadienyltitanium halides

NQR spectra of ³⁵Cl, ⁸¹Br and ¹²⁷I in cyclopentadienyltitanium halides Cp_nTiHal_4-n have been studied. Quadrupole coupling constants of the halogen atoms regularly increase with the increasing number of Cp rings in the molecule, which is apparently connected with the decreasing multiplicity of the TiHal bond. A sharp increase in the asymmetry parameters of the iodine atom on introduction of the Cp rings is evidence for an essential desymmetrization of the electron density in the molecule caused by this operation.     

Polarographisches Verhalten der C1-Halogenkohlenwasserstoffe

Summary Investigations on the polarographic and voltammetric behaviour of organic halogen compounds were carried out in order to obtain indications of how to develop electrochemical determination and detection methods.This first report deals with the polarographic reduction of halogen substituted C₁-compounds. The investigations were performed by means of differential pulse polarography including different supporting electrolytes and solvents. The electrode processes are due to radical reactions.The potentialities of polarographic determinations are discussed.     

基于第一性原理的无铅无机钙钛矿Cs3Bi2X9(X=Cl、Br、I)光电性能表面效应研究

用基于第一性原理的密度泛函理论方法,对Cs₃Bi₂X₉(X=Cl、Br、I)的光电特性进行理论计算,并系统阐述这3种晶体的表面效应对光电性能的影响。结果表明,3种材料的光学特性由铋原子和卤素原子最外层p轨道上的价电子主导。在可见光区中,材料的吸收峰会随卤素原子序数的增加呈现红移,其中一维结构的Cs₃Bi₂Cl₉表面结构在光吸收能力上尤为特别且敏感;二维结构的Cs₃Bi₂Br₉光吸收能力会受厚度影响;零维结构的Cs₃Bi₂I₉非常稳定,且几乎不受表面特性和晶体厚度的影响。     

Étude par spectrométrie de vibration de la structure des composés de coordination de l'acétonitrile avec les halogénures d'aluminium AlCl3 et AlBr3

Infrared and Raman spectra of the three definite coordination compounds formed between CH₃CN or CD₃CN and AlX₃ (X = CI or Br) have been recorded and discussed. All the compounds are ionic and contain AIX₄^? anions. The cation is (AI(CH₃CN)₆]^3? for the AlX₃-1.5 CH₃CN and AlX₃-2 CH₃CN. In the first case, the cation is highly symmetrical and the spectra are consistent with the O_h point group. In the second case, the cation is distorted and the symmetry type may be lower than D_3d or D_4h. The frequencies are correlated with the nature of the halogen. The cations of the 1-1 compounds contain one or two halogen atoms. The vibrational spectra of AlBr₃-CH₃CN are consistent with a [Al(CH₃CN)₂Br₂]^* - AlBr₄^? structure but are more difficult to interpret for the AlCl₃-CH₃CN complex.     

基于第一性原理的无铅无机钙钛矿Cs3Bi2X9(X=Cl、Br、I)光电性能表面效应研究

用基于第一性原理的密度泛函理论方法,对Cs₃Bi₂X₉（X=Cl、Br、I）的光电特性进行理论计算,并系统阐述这3种晶体的表面效应对光电性能的影响。结果表明,3种材料的光学特性由铋原子和卤素原子最外层p轨道上的价电子主导。在可见光区中,材料的吸收峰会随卤素原子序数的增加呈现红移,其中一维结构的Cs₃Bi₂Cl₉表面结构在光吸收能力上尤为特别且敏感;二维结构的Cs₃Bi₂Br₉光吸收能力会受厚度影响;零维结构的Cs₃Bi₂I₉非常稳定,且几乎不受表面特性和晶体厚度的影响。     

Coincidence studies of fluorescence and dissociation processes in electronic excited states of I2+, Br2+, IBr+ and ICl+

The PIFCO technique in which mass-selected photoion—fluorescence photon coincidences are counted, was used to investigate whether I₂⁺, IBr⁺ and ICl⁺ fluoresce. Measurements were made of lifetimes and fluorescence quantum yields of electronic excited states of these ions. Emission was discovered for I₂⁺ and IBr⁺, but ICl⁺ apparently does not fluoresce. Information on the radiative properties of Br₂⁺ was obtained as a by-product of the work on IBr⁺. Fragment ion kinetic energy releases were determined and provide information on dissociative ionization processes in the halogen and interhalogen ions studied.     

Synthesis and structure of halogen derivatives of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-Me2S-7,8-C2B9H11]

Halogenation of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-SMe₂-7,8-C₂B₉H₁₁] with N-chlorosuccinimide, bromine and iodine gave the expected corresponding halogen derivatives [9-SMe₂-11-X-7,8-C₂B₉H₁₀], where X = Cl (1), Br (2), I (3). In the bromination reaction, [9-SMe₂-6-Br-7,8-C₂B₉H₁₀] (4) was isolated as a minor product being the first example of substitution at a “lower” belt of the 7,8-dicarba-nido-undecaborate cage. The use of excess of bromine resulted in dibromo derivative [9-SMe₂-6,11-Br₂-7,8-C₂B₉H₉] (5). Structures of the compounds prepared were determined using ¹¹B-¹¹B COSY NMR spectroscopy (for all halogen derivatives) and single crystal X-ray diffraction (for compounds 2, 3, and 5).     

Stabilization of Mo6S8 by halogens; new superconducting compounds: Mo6S6Br2, Mo6S6I2

We present a study of the properties of the series Mo₆X_8?xY_x (X = S, Se, Te; Y = Br, I) having the hexagonal rhombohedral structure of the PbMo₆S₈ type. For X = S we have found two new superconducting compounds Mo₆S₆Br₂ and Mo₆S₆I₂, having critical temperatures of 13.8 and 14.0°K, respectively. We further find that Mo₆Te₈ becomes superconducting (T_c ≈ 2.6°K) upon substitution of Te by small quantities of iodine, and that in the case of Mo₆Se₈ substitution of a Se atom by a halogen, raises T_c up to about 7.6°K.     

Vibrationally excited NO2 from CH3NO2 and 2-C3H7NO2 photodissociation

We observe vibrationally excited NO₂ from photodissociation of CH₃NO₂ and 2-C₃H₇NO₂ by means of laser induced fluorescence. This approximate method shows very large vibrational excitation in all frequencies of NO₂. The result is interpreted as an indirect predissociation.     

The infrared matrix isolation spectra and normal coordinate analysis of LiBeF3 and the related species Li2BeF4 and (LiBeF3)2

Beryllium fluoride vapor was reacted with ⁶Lif: and ⁷LiF at 900–1000 °C in an effusion tube. The infrared spectrum of the effusate was obtained in a neon matrix, in the range 4000-190 cm^?1. One mixed halide, LiBeF₃ was identified and the existence of (LiBeF₃)₂ or Li₂BeF₄ inferred. For LiBeF₃ seven of the possible nine infrared frequencies were observed. A normal coordinate analysis for LiBeF₃ is presented and used to assign the experimental frequencies. Calculated mean amplitudes of vibration and calculated frequencies from normal coordinate analyses of Li₂BeF₄ and (LiBeF₃)₂ are reported.     

Stereospecific polymerization of propylene on systems TiX3-AlEt3

It has been shown that replacement of Cl atoms by I and Br atoms leads to decrease in the activity of the catalytis systems TiCl₃-AlEt₃ owing to decrease in the number of active centres. This decrease is probably due to the fact that a group of titanium atoms bound by halogen bridges, and not a single atom, is involved in the catalytis act. The most effective way of enhancing the isospecificity of the active centre is to induce the iodine-containing compound to act upon the TiCl₃ crystal surface. However, no simple correlation between the stereospecificity of the catalytis systems, ion radii of the anions and distances M-M and M-X was found.