大苞雪莲内酯的分子结构和晶体结构

新疆雪莲(Saussurea involucrata Kar. et Kin)为我国西北地区名贵中草药,可用于治疗风湿性关节炎和妇科疾病,从中分离得到一种新的倍半萜内酯的β葡萄糖苷,命名为大苞雪莲内酯(右图),其结晶为无色透明针状,m.p.219～221℃。     

Crystal and Molecular Structures of 3-Carboxypropyltriphenylphosphonium Diiodobromide

Complexation in the 3-carboxypropyltriphenylphosphonium bromide–molecular iodine system in chloroform was studied. The maximum number of iodine molecules coordinated by 3-carboxypropyltriphenylphosphonium bromide was established by the spectrophotometric method using a function of the average-iodine number, and the stability constant of the complex was determined. The [(C₆H₅)₃P(CH₂)₃COOH]BrI₂ diiodobromide was studied by X-ray diffraction analysis. The characteristic feature of the crystalline salt was the formation of dimer associates: anionic associates were formed due to the Br···Br intermolecular interactions and cationic associates were formed due to the O···H–O hydrogen bonds. The data obtained were correlated to the results of quantum-chemical calculations.     

对氯苯基硫脲和2,4,6-三溴苯基硫脲的晶体结构和分子结构

本文报道对氯苯基硫脲(Ⅰ)和2,4,6-三溴苯基硫脲(Ⅱ)的晶体结构和分子结构,(Ⅰ)属单斜晶系,空间群P2_1/a,a=10.671(1),b=8.912(1),c=9.128(1),β=106.85(1)°,Z=4,D_c=1.492g/cm~(-3),最后的偏离因子R=0.029,R_w=0.031;(Ⅱ)属正交晶系,空间群Pcab,a=9.997(2),b=7.876(4),c=27.920(3),Z=8,D_c=2.35g/cm~(-3),最后的偏离因子R=0.047,R_w=0.047。晶体结构测定结果表明,硫脲部分的四个原子组成平面三角形,苯环平面与硫脲平面的夹角分别为70.1°和80.3°。     

Crystal and Molecular Structures of Phosphonolactone Derivatives of Chromone

The crystal structure of chromone hydrazonium salt (±)-1-hydroxy-1-oxo-3-phenyl-1,3-dihydro-1λ⁵-2,1-oxaphospholo[4,5-b]-4H-1-benzopyran-4-one (2) and its acid (±)-1-hydroxy-1-oxo-3-phenyl-1,3-dihydro-1λ⁵-2,1-oxaphospholo[4,5-b]-4H-1-benzopyran-4-one (3) have been solved. Condensed rings are almost planar, the P atom adopts nearly tetragonal geometry. The molecular packing is influenced by inter- and intramolecular contacts, which can be recognized as hydrogen bonds.     

Crystal and Molecular Structures of Benzylideneaniline,Benzylideneaniline-p-carboxylic acid and p-methylbenzylidene-p-nitroaniline

The structures of the title compounds have been established by X-ray crystal structure analysis, based on three-dimensional diffractometer data. Bond lengths and angles are given, and the thermal motion of the molecules in the crystals is discussed. The most striking feature of all three molecules is the twist of the aniline ring out of the C? N?C? C plane by 41–55°.     

Molecular and Crystal Structures of TeCl4-Allylalcohol and -Allylacetate Adducts

1,2-electrophilic addition of TeCl₄ to the C=C bond of allylalcohol is observed, while with allylacetate, 1,3-addition occurs, due to migration of the acetate group. The allylalcohol adduct comprises two different kinds of molecules in the solid state, Cl₃Te[CH₂CH(Cl)CH₂OH→] and Cl₂Te[CH₂CH(Cl)CH₂CH-], with dative Te←O and covalent Te-O bonds, five-membered ring structures and Cl-Te?Cl and O-H?O bridges linking the different molecules. In the allylacetate adduct, Cl₃Te[CH₂CH(CH₂Cl)OC(CH₃)=O→], a six-membered ring is formed via an intramolecular dative Te←O interaction, the molecules being linked via C-Cl?Te bridges. Multinuclear NMR spectroscopy and ¹H-¹H-NOESY combined with ab initio (MP2/LANL2DZP) geometry optimisation show the geometry of the ring structures in solution to be similar to those in the solid state.     

Rare-Earth Elements in Molecular Conductors: Crystal and Electronic Structures

The new molecular conductors with some rare-earth metal-complex anions (ET)₅[M(NCS)₆NO₃]·C₂H₅OH (M=Dy (1), Y (2), Ho (3)) and (TMTSF)₃[Y(NO₃)₅]·2C₆H₅Cl (4) as well as a new low-temperature modification of tetra-n-buthylammonium dysprosium(III) complex, (Bu₄N)₃[Dy(NCS)₄(NO₃)₂] (5) used for the preparation of salt 1 were synthesized and studied by X-ray crystallography at 295 and 110 K. Salts 1-3 have a layered crystal structure with a new packing type of the radical cation layers, called an ω-type. Electronic structure calculations for the compounds 1-3 showed that the paired ET molecules have a positive charge +1 and the single ET molecules are neutral. The directions of the TMTSF stacks in the neighboring organic layers of 4 are practically perpendicular so that salt 4 can be regarded as a precursor of 2D conductors formed by mutually perpendicular directions of conductivity.     

投影图在分子结构及晶体结构学习中的应用

介绍投影图在展示分子及晶体中的对称元素、点阵抽取及了解密堆积中空隙分布情况等方面的应用。     

The Crystal and Molecular Structures of Two Acid-Catalysed Rearrangement Products of Taxochinon

The structures of two acid catalysed rearrangement products of taxochinone ( 1 ) have been determined by X-ray analysis. One of the products turned out to be a 20 (10→9) abeo-abietane ( 2 ), the other an optically inactive phenalenone ( 3 ). Crystals of the former compound, C₂₀H₂₆O₃, belong to space group P2₁2₁2₁ with four molecules per cell and the structure was refined with 879 significant reflexions to R = 0.032. Crystals of the latter compound, C₂₀H₂₂O₂, belong to space group P2₁/c with 12 molecules per cell and the structure was refined with 1823 significant reflexions to R = 0.058.     

3,6—二〔二甲氨基〕二苯并碘六圜氯化物的晶体和分子结构

3,6—二[二甲氨基]二苯并碘六圆氯化物的晶体呈淡黄色六棱柱状。该晶体所属的空间群是P2_1/n,晶胞参数为;a=11.073(2),b=13.766(1),c=11.229(11),β=99.36(5)°,Z=4。在CAD—4四圆衍射仪上用Mo-Kα射线收录了Ⅰ≥3σ(Ⅰ)的独立衍射数据2293个。晶体结构用重原子法解出,晶体结构参数经全矩阵最小二乘方法修正,偏离因子R=0.085。 结构测定结果表明,分子中二苯环不共面,其二面交角约为133°。值得指出的是,围绕对称心成心对称的一对分子呈二聚状态。二聚体中二碘原子、二氯原子及与碘原子毗邻的四个碳原子共处于一个平面。二聚体中I—C1间距有3.074和3.102两种,围绕碘原子的四个键角值为90°左右。在二聚体中碘原子以dsp~2。杂化轨道与周围的二氯原子、二碳原子键合。     

锆簇基纳米分子胶囊的合成、晶体结构和荧光性质

选取4,4''-联苯二甲酸（4,4''-H₂BPDC）和2,6-萘二甲酸（2,6-H₂NDC）分别与二氯二茂锆（Cp₂ZrCl₂）反应制备了2例结构新颖的锆基纳米分子胶囊[Cp₃Zr₃（μ₃-O）（μ₂-OH）₃]₂（BPDC）₃Cl₂·H₂O（Zr-MC-1）和[Cp₃Zr₃（μ₃-O）（μ₂-OH）₃]₂（NDC）₃Cl₂·3H₂O（Zr-MC-2）。这2个分子胶囊均由3个线性羧基配体桥联2个三核茂锆建筑单元构成。利用单晶X射线衍射、粉末X射线衍射、元素分析、红外光谱、热重分析和氮气吸附-脱附等手段对化合物进行了表征。此外,荧光光谱分析表明Zr-MC-1和Zr-MC-2分别为深蓝光和蓝光发射材料,其最大发射波长分别为404和456 nm。     

Crystal Structure of Bis(dibenzo-18-crown-6)rubidium Triiodide

Crystalline bis(dibenzo-18-crown-6)rubidium triiodide complex [Rb(DB18C6)₂]⁺ · I₃ ^– (I) is synthesized and its structure is studied by X-ray diffraction analysis. The structure of I (space group Pnma, a = 23.854 Å, b = 23.612 Å, c = 7.863 Å, Z = 4) is solved by the direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.079 against 3990 independent reflections (CAD4 automated diffractometer, MoK ). Structural units of crystal I are the I₃ ^– anions and [Rb(DB18C6)₂]⁺ cations. The crystal has the structure intermediate between that of a standard host–guest complex and a sandwich complex. In the structure of complex I, the crystallographic plane with symmetry m passes through the I₃ ^– anion (perpendicularly to its axis) and complex cation. The coordination polyhedron of the Rb⁺ cation is a strongly distorted hexagonal pyramid with the O atom of one crown ligand at the axial vertex and a base of six O atoms of another DB18C6 crown ligand.     

Chiral and Achiral Crystal Structures

An extensive study and analysis of the concepts, classification, presentation, and nomenclature of chirality and lack of chirality in crystal structures and their constituents is presented. Oriented crystal structures are classified. The chirality rules for existence of molecular crystal structures are examined and the relation to segmentation and latent symmetry highlighted. The nomenclature of chirality and related terms, and the relationship of chirality to optical activity is covered. The uses and limitations of the Euclidean normalizer are treated. An improved glossary of terms is included.     

Crystal Structures of O－Vanillin－semicarbazide and Salicylaldehyde－semicarbazide

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基于席夫碱配合物的分子磁体：合成、结构和磁学性质

基于席夫碱配合物的分子磁体：合成、结构和磁学性质;席夫碱;配位聚合物;晶体结构;磁学性质     

Disubstituted Rubidium Orthoperiodate Rb2H3IO6: Crystal and Molecular Structures and Properties

The crystal and molecular structures of acid salt Rb₂H₃IO₆ were determined. The anion part of the structure is united via a hydrogen bonding system to form a layer parallel to the xy plane. The proton conductivity in the temperature range of 40–60°C was found to be 10^–7–5 × 10^–6 Ohm^–1cm^–1, E _a = 2 eV.     

不同SnO2晶体结构的力学性能及电子结构

采用基于密度泛函理论(DFT)的平面波超软赝势法,用广义梯度近似(GGA)PBE交换相关泛函,对高压相变产生五种不同 SnO2晶体结构的电子结构和力学性质进行了第一性原理计算.计算结果表明,Pnam型SnO2的形成相对困难,体模量较大,Pbca和Pnam型SnO2的维氏硬度值相差不明显.不同晶体结构的带隙存在差异,导带区域电子分布和弥散程度大于价带区域,局域性差.五种SnO2晶体结构的价带部分约在-10-0 eV和-20--15 eV处,主要贡献来自于O2p、2s轨道.光学性质计算表明,Pnam结构对紫外波段光的吸收最明显,同时给出电子轨道跃迁规律.