The Evolution of Terminal Allylphosphinidene Pentacarbonyltungsten Complex

Abstract

DFT computations suggest that terminal allylphosphinidene pentacarbonyltungsten complex 1 can evolve either by intramolecular P + C?C cycloaddition or by [1,2] H C to P shift to give 2 or 6. Upon thermolysis of the 7-allyl-7-phosphanorbornadiene precursor, the transient complex 1 gives two diastereomeric dimers 4a,b deriving from a head-to-tail P + C?C intermolecular cycloaddition and another dimer 5 deriving from the [4 + 1] cycloaddition of 1 with 6, followed by an intramolecular hydrophosphination.     

The X-ray Structure of the Complex Dichloroorthovinyldiphenylarsineplatinum(II)

The X-ray structure analysis of the olefinic tertiary arsine complex dichloro$\text{ortho}$vinyldiphenylarsineplatinum(II) shows a square planar coordination geometry with the coordinated olefin making an angle of 83.6° with this plane.     

混合配体的铜(Ⅱ)配合［Cu(C2H4O2N)(C12H8N2)(H2O)］.ClO4.2.5H2O的合成、性质及晶体结构

本文对甘氨酸、1,10-邻菲咯啉铜(Ⅱ)固体配合物进行了合成和表征,并利用X射线分析研究了其晶体结构。     

新型一维麻花状超分子配合物的合成与结构

具有特殊结构及性能的超分子化合物由于其结构上的新颖性及潜在的应用价值而成为人们关注的热点 .以一个苯环为间隔基两端含两个吡啶基团的配体 L1与 Pd( ) ,Pt( )形成 2 -索烃 [1 ] ,与Cd( NO3) 2 则形成具有一维平面结构的聚合物 [2 ] .以联苯为间隔基的配体 L2在 4 ,4′-二联吡啶共同作用下与 Pd( )形成 2 -索烃 [3] .同样以一个苯环为间隔基两端含两个咪唑基团的配体 L3与 Zn( NO3) 2 ,Ag NO3反应得到新型多聚轮烷配合物 [4,5 ] .研究结果表明 ,配体或配位金属离子等的微小差别即导致形成结构不同的超分子化合物 .但这些超分子…     

Contrast-Matched Small-Angle X-ray Scattering from a Heavy-Atom-Labeled Protein in Structure Determination: Application to a Lead-Substituted Calmodulin-Peptide Complex

The information content in 1-D solution X-ray scattering profiles is generally restricted to low-resolution shape and size information that, on its own, cannot lead to unique 3-D structures of biological macromolecules comparable to all-atom models derived from X-ray crystallography or NMR spectroscopy. Here we show that contrast-matched X-ray scattering data collected on a protein incorporating specific heavy-atom labels in 65% aqueous sucrose buffer can dramatically enhance the power of conventional small- and wide-angle X-ray scattering (SAXS/WAXS) measurements. Under contrast-matching conditions the protein is effectively invisible and the main contribution to the X-ray scattering intensity arises from the heavy atoms, allowing direct extraction of pairwise distances between them. In combination with conventional aqueous SAXS/WAXS data, supplemented by NMR-derived residual dipolar couplings (RDCs) measured in a weakly aligning medium, we show that it is possible to position protein domains relative to one another within a precision of 1 ?. We demonstrate this approach with respect to the determination of domain positions in a complex between calmodulin, in which the four Ca(2+) ions have been substituted by Pb(2+), and a target peptide. The uniqueness of the resulting solution is established by an exhaustive search over all models compatible with the experimental data, and could not have been achieved using aqueous SAXS and RDC data alone. Moreover, we show that the correct structural solution can be recovered using only contrast-matched SAXS and aqueous SAXS/WAXS data.     

Structure and Magnetic Properties of a Manganese Complex with 1-Carboxymethylpyridinium-3-carboxylate

One complex with a zwitterionic dicarboxylate ligand,[Mn(L)(N3)]n1(L=1-carboxymethylpyridinium-3-carboxylate),was synthesized and structurally characterized.Complex 1crystallizes in triclinic,space group P1 with a=7.570(2),b=7.808(2),c=9.232(3),=94.450(19)o,V=489.0(3)3,Z=2,Mr=277.11,Dc=1.882 g/cm3,F(000)=278,μ=1.359 mm-1,S=1.021,the final R=0.0509 and wR=0.1149 for 2236 observed reflections with I2(I).Complex 1 consists of two-dimensional coordination layers in which the anionic uniform chains with mixed triple bridges(one end-on(EO)azide and two syn-syn carboxylates)are cross-linked by the flexible cationic N-methylpyridinium spacers.Magnetic studies demonstrated that the triple bridge in 1 transmits antiferromagnetic coupling between the Mn(II)ions.     

Synthesis and Structure of a Titanocene-ferrocenyl Complex

A titanocene-ferrocenyl complex, （5-ferrocenyl-2-hydroxybenzenecarboxylato- O,O′）-bis（methylcyclopentadienyl）titanium（IV） 4, and an unexpected ionic complex, [C7H8NO3]- [（C5H5）Fe（C5H4）SO3]·H2O3 were synthesized and characterized by IR, ^1H NMR and elemental analysis. Compound 3 is of triclinic, space group P1 with a = 5.954（2）, b = 13.208（5）, c = 13.252（5） A, α = 60.993（7）,β = 84.342（8）,γ = 86.933（8）°, Z = 2, V = 906.8（6）A^3, Dc = 1.601 g/cm^3, μ（MoKα） = 0.987 mm^-1, F（000） = 452, the final R = 0.0647 and wR = 0.1333 for 2311 observed reflections （I 〉 2σ（I））. Compound 4 belongs to the monoclinic system, space group P2 1/c with α = 14.3310（9）, b = 12.5065（8）, c = 12.9406（10） A, β = 95.101（4）°, Z = 4, V = 2310.2（3） A^3, Dc = 1.513 g/cm^3, μ（MoKα） = 1.004 mm^-1, F（000） = 1088, the final R = 0.0461 and wR = 0.1048 for 2112 observed reflections （1 〉 2σ（I））.     

X射线晶体学结合电子晶体学在复杂无机晶体结构解析中的应用

自然界中的材料,比如无机材料,有机材料,生物材料等等,均有其独特的物理和化学性质。而材料的性能又与材料的结构息息相关,只有充分了解了材料的结构,才能更加深入的研究材料性质。因此,材料结构的确定在化学、物理、生物等学科中的显得尤为重要。X射线晶体学作为传统的结构解析技术仍然是目前最重要的结构解析手段,但是对于复杂结构,X射线衍射晶体学解析结构也存在一些不足,往往需要其他技术手段相补充才能完成复杂结构的结构解析。电子晶体学虽然起步比X射线晶体学晚,但是,经过近几十年的发展,已经是结构解析领域一个非常重要的手段。本文将主要介绍X射线晶体学结合电子晶体学在复杂无机晶体结构解析中的应用。     

Hydrothermal Synthesis,Crystal Structure and Thermal Properties of a Novel Samarium Complex with 1D Nano-chain Structure

1 Introduction The design and construction of metal-organic polymers has been a field of rapid growth in materials chemistry because of their intriguing topologies and potential applications as functional materials[1―6]. In     

Molecular Structure of 1-Germatrahol and its Complex With Chloroform

The crystal structures of anhydrous 1-germatranol and its complex with HCCl₃ are centrosymmetrical dimers because of their intermolecular hydrogen bonds. In the germatranol crystal, the axial and equatorial oxygen atoms of its two molecules are hydrogen bonded into an eight-membered coordination cycle. In the complex with HCCl₃, the two molecules of germatranol are likewise linked in dimers, and both axial oxygen atoms are H bonded with HCCl₃. In the investigated structures, the axial Ge—O bond is shorter than the equatorial ones. Depending on the number and strength of the hydrogen bonds, the interatomic Ge—O and Ge ← N distances change markedly. The quantitative estimates of the H bond energy are obtained from quantum chemical calculations of the model systems containing 1-germatranol and HCCl₃ molecules.     

Facile Synthesis of Pentacarbonyltungsten(0) Complexes with Oxaphosphirane Ligands

Facile synthesis of tungsten(0) complexes of the type 7a – g (R¹ = C₅Me₅) and 8a – g (R¹ = CH(SiMe₃)₂) using transient Li/Cl phosphanylidenoid tungsten(0) complexes 4 , 5 and carbonyl derivatives 6a – g is reported; furthermore, for all complexes NMR, IR spectroscopic, mass spectrometric investigations and, in addition, single‐crystal X‐ray structures of complexes 7b , d – g and 8b , d are presented.     

Structure and Population of Complex Ionic Species in FeCl2 Aqueous Solution by X-ray Absorption Spectroscopy

Technologies for mass production require cheap and abundant materials such as ferrous chloride (FeCl₂). The literature survey shows the lack of experimental studies to validate theoretical conclusions related to the population of ionic Fe-species in the aqueous FeCl₂ solution. Here, we present an in situ X-ray absorption study of the structure of the ionic species in the FeCl₂ aqueous solution at different concentrations (1–4 molL⁻¹) and temperatures (25–80 °C). We found that at low temperature and low FeCl₂ concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five water molecules at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical water molecule is substituted by a chlorine ion to yield a neutral Fe[Cl₂(H₂O)₄]⁰. The observed substitutional mechanism is facilitated by the presence of the intramolecular hydrogen bonds as well as entropic reasons. The transition from the single charged Fe[Cl(H₂O)₅]⁺ to the neutral Fe[Cl₂(H₂O)₄]⁰ causes a significant drop in the solution conductivity, which well correlates with the existing conductivity models.     

六(3,3-二甲基-1-(1H-1,2,4-三唑)-2-丁酮)锌高氯酸盐配合物的合成及晶体结构

3，3-二甲基-1－（1H－1，2，4-三唑）－2-丁酮的锌配合物（C48H78Cl2N18O14Zn）已被合成。X-射线衍射结构分析表明，晶体属单斜晶系，空间群P21／n，晶体学数据：晶体体积结构偏离因子，标题配合物分子中6个三唑环上的4位N原子与Zn原子配位，形成八面体结构，锌原子处在结晶学的对称中心上。