Synthesis and Crystal Structure of Dicesium trans Dicarbonatotetraaquomagnesium, Cs_2[Mg(CO_3)_2(H_2O)_4]

ＩｎｔｒｏｄｕｃｔｉｏｎＰｒｅｖｉｏｕｓｌｙ,ｗｅｒｅｐｏｒｔｅｄｔｈｅｃｒｙｓｔａｌｓｔｒｕｃｔｕｒｅｏｆＫ２［Ｎｉ（ＣＯ３）２（Ｈ２Ｏ）４］［１］,ｗｈｉｃｈｃｒｙｓｔａｌｌｉｚｅｄｉｎｔｈｅｂａｙｌｉｓｓｉｔｅｔｙｐｅｓｔｒｕｃｔｕｒｅａｎｄｗａｓｆｏｕｎｄｔｏｂｅｉｓｏｓｔｒｕｃｔｕｒａｌｗｉｔｈＫ２［Ｃｏ（ＣＯ３）２（Ｈ２Ｏ）４］［２］ａｎｄＫ２Ｍｇ（ＣＯ３）２·４Ｈ２Ｏ［３］．Ｉｎｏｒｄｅｒｔｏｓｙｓｔｅｍａｔｉｃａｌｌｙｉｎｖｅｓｔｉｇａｔｅｔｈｅｏｃｃｕｒｒｅｎｃｅｏｆｔｈｅｃｏ…     

南蛇藤昆虫拒食成分的研究(I)

南蛇藤昆虫拒食成分的研究（Ｉ）王明安,陈馥衡（北京农业大学应用化学系,北京,１０００９４）关键词南蛇藤,倍半萜,结构分析南蛇藤（Ｃｅｌａｓｔｒｕｓｏｒｂｉｃｕｌａｔｕｓ）是我国传统的低毒杀虫植物,其主要化学成分为倍半萜［１］．Ｓｍｉｔｈ等［２,３］对...     

A Rule to Design High Spin Molecules with Hetero spin Centers

ＩｎｔｒｏｄｕｃｔｉｏｎＨｉｇｈｓｐｉｎｍｏｌｅｃｕｌｅｓｈａｖｅａｔｔｒａｃｔｅｄｍｕｃｈｉｎｔｅｒｅｓｔ,ｂｅｃａｕｓｅｔｈｅｙｃａｎｂｅｓｅｒｖｅｄａｓｔｈｅｂｕｉｌｄｉｎｇｂｌｏｃｋｆｏｒｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓ［１－２］．ＩｔｉｓｓｕｇｇｅｓｔｅｄｂｙＦｕｋｕｔｏｍｅ［３］ａｎｄＤｏｕｇｈｅｒｔｙｅｔａｌ．［４］ｔｈａｔｔｈｅｈｉｇｈｓｐｉｎｍｏｌｅｃｕｌｅｓｃａｎｂｅｄｉｖｉｄｅｄｉｎｔｏｔｗｏｃｏｍｐｏｎｅｎｔｓ：ｔｈｅｓｐｉｎ－ｃｏｎｔａｉｎｉｎｇ（ＳＣ）ｆｒａｇｍｅｎ…     

有机化合物中二级化学键的理论研究(Ⅳ)——喹啉基氮杂大环铜配合物中的二级化学键

前文［１,２］报道了二级化学键存在于若干金属有机化合物以及某些簇合物中,实际上,在Ｆｉｇ．１ＣｒｙｓｔａｌｓｔｒｕｃｔｕｒｅｏｆＣｕＬ２［１４］┐２ｑｕ某些配合物体系中亦存在着二级化学键．本文将着重研究喹啉基氮杂环铜配合物（ＣｕＬ２［１４］－２ｑｕ）...     

自组装膜修饰悬汞电极的制备及电化学特性

电子跨膜传递一直是生物能学的中心问题 ,长期以来生物学家和化学家一直为能在分子水平上研究生物膜上电子传递过程的模型体系而不懈努力．提出的模型体系有平板双分子层膜（ｐｌａｎｎｅｒｂｉｌａｙｅｒｌｉｐｉｄｍｅｍｂｒａｎｅ,ＢＬＭ）［１］、泡囊［２］、和固体支撑双分子层膜（ｓｏｌｉｄｓｕｐｐｏｒｔｅｄｂｉｌａｙｅｒｌｉｐｉｄｍｅｍｂｒａｎｅ ,Ｓ ＢＬＭ）［３］等 ,ＢＬＭ膜与实际生物膜最为相似 ,但极不稳定 ;Ｓ ＢＬＭ膜稳定性好 ,但基底不平 ,缺陷大 ,研究电子跨膜传递困难．而８０年代初 ,自组装(Ｓｅｌｆ Ａｓｓｅ…     

Heteropolytungstates Containing Organotin and Cobalt or Zinc Atom

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｒｅｃｅｎｔｙｅａｒｓ，ｔｈｅｐｈａｒｍａｃｅｕｔｉｃａｌｃｈｅｍｉｓｔｒｙｏｆｐｏｌｙｏｘｏｍｅｔａｌｌａｔｅｓ（ＰＯＭｓ）ｈａｓａｔｔｒａｃｔ－ｅｄｍｕｃｈａｔｔｅｎｔｉｏｎ［１，２］．Ｉｎｏｒｄｅｒｔｏｄｅｖｅｌｏｐｍｏｒｅｈｉｇｈｌｙｅｆｆｅｃｔｉｖｅ，ｌｏｗｔｏｘｉｃａｎｔｉｖｉｒａｌａｎｄａｎｔｉ－ｔｕｍｏｒａｌａｇｅｎｔｓ，ａｔｔｅｍｐｔｓｈａｖｅｂｅｅｎｍａｄｅｔｏｍｏｄｉｆｙｔｈｅｗｅｌｌ－ｋｎｏｗｎＫｅｇｇｉｎａｎｉｏｎｓ［Ｘｎ－Ｗ１２Ｏ４０］（８…     

cis－［Pt（NH_3）_2Cl_2］和trans－［Pt（NH_3）_2Cl_2］的微型合成

ｃｉｓ－［Ｐｔ（ＮＨ_３）_２Ｃｌ_２］和ｔｒａｎｓ－［Ｐｔ（ＮＨ_３）_２Ｃｌ_２］的微型合成袁书玉，来月英（清华大学化学系，北京１０００８４）ｃｉｓ－［Ｐｔ（ＮＨ２）２Ｃｌ２］为一抗癌药物，而它的反式异构体却没有这一特性。其原因也已在进行研究［１］。由...     

[Fe(CN)_6]~(4-)还原trans-[Co(en)_2(ImH_)2]~(3+)的电子转移反应动力学机理

在不同的温度下，考察了六氰合铁（Ⅱ）配阴离子［Ｆｅ（ＣＮ）６］４－还原ｔｒａｎｓ－［Ｃｏ（ｅｎ）２（ＩｍＨ）２］３＋的反应动力学。结果表明，反应遵循Ｈ．Ｔａｕｂｅ所提出的外配位界电子传递机理。在２５℃，Ｉ＝０．５ｍｏｌ·Ｌ－１，ｔｒａｎｓ－［Ｃｏ（ｅｎ）２（ＩｍＨ）２］３＋／［Ｆｅ（ＣＮ）６］４－反应体系的前驱配合物离子对形成常数为Ｑ１ｐ＝９８．９ｍｏｌ－１·Ｌ，电子转换速率常数为Ｋｅｔ＝１．３×１０－４ｓ－１，电子转移过程活化焓ΔＨ≠ｅｔ和活化熵ΔＳ≠ｅｔ分别为１４１．２ｋＪ·ｍｏｌ－１、５７３．５Ｊ·ｍｏｌ－１·Ｋ－１。     

Syntheses and Liquid Crystal Properties of New Rare Earth Sandwich-Type Heteropoly Compounds

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅｓａｎｄｗｉｃｈ－ｔｙｐｅｃｏｍｐｏｕｎｄｓｏｆｆｏｒｍｕｌａ［Ｍ４（Ｈ２Ｏ）２（Ｐ２Ｗ１５Ｏ５６）２］ｎ－ｗｅｒｅｆｉｒｓｔｌｙｄｅ－ｓｃｒｉｂｅｄｂｙＦｉｎｋｅｅｔａｌ．［１］,ａｄｏｚｅｎｏｆｔｈｉｓｋｉｎｄｏｆｃｏｍｐｏｕｎｄｓｈａｖｅｂｅｅｎｓｙｎｔｈｅｓｉｚｅｄ［２,３］,ｉｎｗｈｉｃｈｍｏｓｔｏｆｔｈｅｃｅｎｔｅｒａｔｏｍｓｗｅｒｅｔｒａｎｓｉｔｉｏｎｍｅｔａｌｓ,ｓｕｃｈａｓＭｎ２＋,Ｆｅ３＋,Ｃｏ２＋,Ｎｉ２＋,Ｃｕ２＋,Ｚｎ２＋,Ｃｄ２＋,ａ…     

Studies on Immunoglobulin G in Human Sera from Guillain Barre Syndrome Patient (Ⅱ)——The Determination of the Isoelectric Point of Immunoglobulin G by Capillary Isoelectric Focusing

ＩｎｔｒｏｄｕｃｔｉｏｎＧｕｉｌｌａｉｎ－Ｂａｒｒｅｓｙｎｄｒｏｍｅ（ＧＢＳ）ｉｓｃｏｎｓｉｄｅｒｅｄｔｏｂｅａｎａｕｔｏｉｍｍｕｎｅｄｉｓｏｒｄｅｒｏｆｔｈｅｐｅ－ｒｉｐｈｅｒａｌｎｅｒｖｏｕｓｓｙｓｔｅｍ［１］．ＴｈｅｂａｌａｎｃｅｏｆｓｙｍｐａｔｈｅｔｉｃｎｅｒｖｅｓａｎｄｐａｒａｓｙｍｐａｔｈｅｔｉｃｎｅｒｖｅｓｉｎＧＢＳｐａｔｉｅｎｔｓｉｓｄｉｓｔｕｒｂｅｄ,ｗｈｉｃｈｌｅａｄｓｔｏｃｏｍｐｌｅｔｅｐａｒａｌｙｓｉｓ［１—３］．Ｍｏｓｔｐａｔｉｅｎｔｓｓｈｏｗｔｈｅｔｙｐｉｃａｌｓｙｍ…     

The nature of halogen...halide synthons: theoretical and crystallographic studies

Two types of halogen...halide synthons are investigated on the basis of theoretical and crystallographic studies; the simple halogen...halide synthons and the charge assisted halogen...halide synthons. The former interactions were investigated theoretically (ab initio) by studying the energy of interaction of a halide anion with a halocarbon species as a function of Y...X- separation distance and the C-Y...X- angle in a series of complexes (R-Y...X-, R=methyl, phenyl, acetyl or pyridyl; Y=F, Cl, Br, or I; X-=F-, Cl-, Br-, or I-). The theoretical study of the latter interaction type was investigated in only one system, the [(4BP)Cl]2 dimer, (4BP=4-bromopyrdinium cation). Crystal structure determinations, to complement the latter theoretical calculations, were performed on 13 n-chloropyridinium and n-bromopyridinium halide salts (n=2-4). The theoretical and crystallographic studies indicate that these interactions are controlled by electrostatics and are characterized by linear C-Y...X- angles and separation distances less than the sum of van der Waals radius (rvdW) of the halogen atom and the ionic radii of the halide anion. The strength of these contacts from calculations varies from weak or absent, e.g., H3C-Cl...I-, to very strong, e.g., HCC-I...F- (energy of interaction ca. -153 kJ/mol). The strengths of these contacts are influenced by four factors: (a) the type of the halide anion; (b) the type of the halogen atom; (c) the hybridization of the ipso carbon; (d) the nature of the functional groups. The calculations also show that charge assisted halogen...halide synthons have a comparable strength to simple halogen...halide synthons. The nature of these contacts is explained on the basis of an electrostatic model.     

Substituent effects on noncovalent halogen/π interactions: Theoretical study

Noncovalent halogen/π interactions of FCl with substituted benzenes have been investigated using ab initio calculations. It was shown that the predicted maximum interaction energy gap between the substituted and unsubstituted systems amounts to 1.14 kcal/mol, and therefore substituents on benzene have a pronounced effect on the strength of halogen/π interactions. While the presence of electron‐donating groups (NH₂, CH₃, and OH) on benzene enhances the interaction energy appreciably, an opposite effect is observed for electron‐accepting groups (NO₂, CN, Br, Cl, and F). The large gain of the attraction by electron correlation illustrates that the stabilities of the systems considered arise primarily from the dispersion interaction. Beside the dispersion interaction, the charge‐transfer interaction also plays an important role in halogen/π interactions, as a charge density analysis suggested. To provide more insight into the nature of halogen/π interactions, topological analysis of the electron density distribution and properties of bond critical points were determined in terms of the atoms in molecules (AIM) theory. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Effects of halogen atoms on the mass spectra of some 3-phenylpropionyl halides

The mass spectra of the title compounds have been studied by use of deuterium labelling. The character of the halogen atom appears to have a marked influence on the fragmentation pathways. It is shown that the acyl halide group may react with the different active atoms in the molecular ion—the α- and β-hydrogen atoms—as well as with the phenyl ring.     

Halide coordination of perhalocyclohexasilane Si6X12 (X=Cl or Br)

The addition of halide anions (X' = Cl(-), Br(-), or I(-)) to perhalocyclohexasilane Si(6)X(12) (X = Cl or Br) led to the formation of complexes comprising [Si(6)X(12)X'(2)](2-) dianions. An upfield shift in the (29)Si NMR spectra was noted upon coordination, and structural determination by X-ray crystallography showed that the dianions adopt an "inverse sandwich" structure where the six cyclic silicon atoms form a planar hexagon with the two halide anions X' located on the 6-fold axis equally disposed above and below the plane of the Si(6) ring. Additionally, these apical X' atoms are within the van der Waals bonding distance to the silicon ring atoms, indicating a strong interaction between X' and silicon atoms. These results detail crystallographic variations within the halogen series providing further insight into the nature of the Lewis acid sites above and below the Si(6)X(12) ring, where interactions with hard Lewis bases such as halide anions are observed. Interestingly, the stereochemistry of the silicon atoms in [Si(6)X(12)X'(2)](2-) is not affected much by the size or electronegativity of the halogen atoms.     

On the directionality of anion-π interactions

The directionality of two important noncovalent interactions involving aromatic rings (namely anion-π and cation-π) is investigated. It has been recently published that the anion-π interactions observed in X-ray structures where the anion is located exactly over the center of the ring are scarce compared to cation-π interactions. To explain this behavior, we have analyzed how the interaction energy (RI-MP2/aug-cc-pVDZ level of theory) is affected by moving the anion from the center of the ring to several directions in anion-π complexes of chloride with either hexafluorobenzene or trifluoro-s-triazine. We have compared the results with the directionality of the cation-π interaction in the sodium-benzene complex. The results are useful to explain the experimental differences between both ion-π interactions. We have also computed the van der Waals radii of several halide anions and we have compared them to the neutral halogen atoms.     

Interactions of a Mn atom with halogen atoms and stability of its half-filled 3d-shell

Using density functional theory with hybrid exchange-correlation potential, we have calculated the geometrical and electronic structure, relative stability, and electron affinities of MnX(n) compounds (n = 1-6) formed by a Mn atom and halogen atoms X = F, Cl, and Br. Our objective is to examine the extent to which the Mn-X interactions are similar and to elucidate if/how the half-filled 3d-shell of a Mn atom participates in chemical bonding as the number of halogen atoms increases. While the highest oxidation number of the Mn atom in fluorides is considered to be +4, the maximum number of halogen atoms that can be chemically attached in the MnX(n)(-) anions is 6 for X = F, 5 for X = Cl, and 4 for X = Br. The MnCl(n) and MnBr(n) neutrals are superhalogens for n ≥ 3, while the superhalogen behavior of MnF(n) begins with n = 4. These results are explained to be due to the way different halogen atoms interact with the 3d electrons of Mn atom.     

The Role of Molecular Electrostatic Potentials in the Formation of a Halogen Bond in Furan⋅⋅⋅XY and Thiophene⋅⋅⋅XY Complexes

The halogen bonding of furan???XY and thiophene???XY (X=Cl, Br; Y=F, Cl, Br), involving σ‐ and π‐type interactions, was studied by using MP2 calculations and quantum theory of “atoms in molecules” (QTAIM) studies. The negative electrostatic potentials of furan and thiophene, as well as the most positive electrostatic potential (V_S,max) on the surface of the interacting X atom determined the geometries of the complexes. Linear relationships were found between interaction energy and V_S,max of the X atom, indicating that electrostatic interactions play an important role in these halogen‐bonding interactions. The halogen‐bonding interactions in furan???XY and thiophene???XY are weak, “closed‐shell” noncovalent interactions. The linear relationship of topological properties, energy properties, and the integration of interatomic surfaces versus V_S,max of atom X demonstrate the importance of the positive σ hole, as reflected by the computed V_S,max of atom X, in determining the topological properties of the halogen bonds.     

Molecular structure of 4,16-dichloro- and 4,16-dibromo[2.2]-paracyclophanes

Conclusions An x-ray diffraction structural analysis showed that the distortions in the geometries of sterically strained 4,16-dichloro- and 4,16-dibromo[2.2]paracyclophanes are similar to those found in unsubstituted [2.2]paracyclophane. The introduction of bulky halogen atoms at C⁴ and C¹⁶ in the [2.2]paracyclophane molecule does not lead to a marked increase in the steric repulsion of the benzene rings. The polar nature of the halogen atoms leads to dipole-dipole attraction of the antiparallel benzene rings which are drawn somewhat closer to each other and to the halogen atom of the other ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2007–2010, September, 1986.     

Halogen-Driven Bandgap Opening in Graphdiyne for Overall Photocatalytic Water Splitting

In this work, we studied the electronic band structure of the halogen (F, Cl, and Br) functionalized graphdiynes (GDYs) by using hybrid density functional theory. The results revealed that the bandgap energies of modified GDYs increase as the number of halogen atoms increases. It is also found that the position of the valence band maximum (VBM) is influenced by the electronegativity of halogen atoms. The higher the electronegativity, the deeper the VBM of the GDYs modified by the same number of halogen atoms. Importantly, our results revealed that the bandgap of GDY could be effectively tuned by mixing types of halogen atoms. The new generated conduction band and valence band edges are properly aligned with the oxidation and reduction potentials of water. Further thermodynamic analysis confirms that some models with mixing types of halogen atoms exhibit higher performance of overall photocatalytic water splitting than non-mixing models. This work provides useful insights for designing efficient photocatalysts that can be used for overall water splitting.