含茂、非茂混合配体钛族络合物的合成与催化烯烃聚合的研究进展

目前金属有机钛族络合物的发展呈现出多元化的趋势:茂络合物、非茂络合物以及茂非茂混合配体络合物,而其中茂、非茂混合配体络合物是近年来发展的一个新亮点.关于茂钛族络合物、非茂钛族络合物近年已经有过许多的综述,而关于茂、非茂混合配体钛族络合物的综述却很少.综述了近年来茂、非茂混合配体钛族络合物合成与催化烯烃聚合的研究进展.     

Regioselective hydrosilylation of terminal acetylenes via acetylene-Co2(CO)4dppm complex: effects of the ligands in acetylenedicobalt complex

The regioselective hydrosilylation of the acetylenedicobalt complex on the terminal acetylene with special reference to the ligands to produce a vinylsilane is described. It was found that the use of the ligands exchanged dicobalttetracarbonyl bis(diphenylphosphino)methane complex dramatically changed the regioselectivity compared to the corresponding dicobalthexacarbonyl complex.     

Supramolecular approaches to generate libraries of chelating bidentate ligands for homogeneous catalysis

The process of catalyst discovery and development relying on combinatorial methods has suffered so far from the difficult access to structurally diverse and large libraries of ligands, in particular the structurally more complex class of bidentate ligands. A completely new approach to streamline the difficult ligand synthesis process is to use structurally less complex monodentate ligands that self-assemble in the coordination sphere of a metal center through noncovalent attractive ligand-ligand interactions to generate bidentate, chelating ligands. When complementary attractive ligand-ligand interactions are employed, it is even possible to generate libraries of defined chelate-ligand catalysts by simply mixing two different monomeric ligands. This Minireview summarizes the first approaches and results in this new field of combinatorial homogeneous catalysis.     

Sterically controlled formation of monodentate versus chelating carbene ligands from phenylhydrazine

Palladium-templated addition of phenylhydrazine to methylisocyanide led to a Chugaev-type chelating dicarbene–palladium complex that is an effective catalyst for Suzuki-Miyaura cross-coupling reactions of aryl bromides and activated aryl chlorides. In contrast, the use of isopropylisocyanide resulted in an unprecedented complex containing aminohydrazinocarbene ligands, which was characterized by X-ray crystallography. The latter complex represents a possible intermediate in the formation of chelating carbene ligands.     

混配络合物中配位体最佳浓度比的理论研究

我们认为,如金属离子M能与配位体A和B形成二元络合物,那么在配位数允许和不存在空间障碍的情况下,总有三元络合物形成.但由于两种配位体之间的浓度比例调节不当,会造成三元络合物在溶液里的所有组份中占很小的比例,这样,往往给人们一个错觉,即没有三元络合物形成,三元混配络合物在溶液里所有组份中所占的比例达到极大时,两配位体之间的浓度比例是可以通过计算得到的。     

Control of molecular architecture by use of the appropriate ligand isomer: a mononuclear "corner-type" versus a tetranuclear [2 x 2] grid-type cobalt(III) complex

Employing two isomeric pyrazine-based ligands a [2 x 2] grid-type tetranuclear cobalt(III) complex, incorporating doubly deprotonated (La)2- ligands, and a "corner-type" mononuclear cobalt(III) complex, incorporating neutral H2Lp ligands in a zwitterionic form, have been synthesised and structurally characterised.     

Organometallic chemistry of amidate complexes. accelerating effect of bidentate ligands on the reductive elimination of N-aryl amidates from palladium(II)

We report a series of arylpalladium complexes of acetamidate, sulfonamidate, and deprotonated oxazolidinone ligands that undergo reductive elimination with rates and yields that depend on the binding mode of the ancillary and amidate ligands. Complexes of the acetamidate ligands containing the bidentate phosphines DPPF and Xantphos as ancillary ligands undergo reductive elimination. The rate and yield were higher from the complex ligated by Xantphos, which contains a larger bite angle. In contrast, the analogous amidate complex containing a single sterically hindered monodentate ligand and a kappa2-bound amidate ligand does not undergo reductive elimination. This trend of faster reductive elimination from complexes containing bidentate ancillary ligands than from a complex with a single monodentate ancillary ligand is unusual and is consistent with an effect of the denticity of the ancillary ligand on the binding mode of the amidate. Complexes of sulfonamidate ligands underwent reductive elimination faster than complexes of acetamidates, and reductive elimination occurred from complexes containing both bidentate and monodentate ancillary ligands. Like reductive elimination from the acetamidate complexes, reductive eliminations from the sulfonamidate complexes were faster when the complexes possessed bidentate Xantphos and kappa1-sulfonamidate ligands.     

Synthesis, characterization, and antibacterial activity of a cobalt(II) Schiff base complex derived from pyridoxal and sulfanilic acid

Reaction of pyridoxal hydrochloride and sulfanilic acid with CoCl₂ in aqueous methanol solution afforded a Co(II) Schiff base complex, which was characterized by physico-chemical and spectroscopic methods. The structure of the complex was determined by single crystal X-ray diffraction. In the complex, the Co(II) is sandwiched at the edge of two parallel Schiff base ligands, being coordinated by two phenolic O and two imine N atoms of two Schiff base ligands plus two O atoms of water ligands, forming a distorted octahedral coordination environment. Thermal stability measurements showed that the skeleton of the complex is stable up to 500?K. The antibacterial activity of the complex was screened using the paper disc diffusion method.     

Preparation, structure and catalytic activity of copper(II) complexes of novel 4,4′-BOX ligands

This Letter details the synthesis of two new 4,4′-bisoxazoline (BOX) ligands. The copper(II) complex of one of the new ligands is structurally determined. The catalytic performance of the copper(II) complexes of the novel ligands, and that of our recently described phenyl AraBOX ligand in Diels-Alder reactions are reported. We have used the structural information to propose an explanation of a curious variation in the diastereoselectivity obtained in the case of one ligand complex.     

Bimetallic reactivity. Preparation and properties of bimetallic complexes formed by binucleating ligands bearing 4- and 6-coordinate sites

Four binucleating ligands bearing 4- and 6-coordinate sites employing phenolate bridges have been prepared. Bimetallic copper(II) and nickel(II) complexes of some of these ligands have been isolated and characterized. Crystal structures of two of the copper(II) complexes have been determined. A monometallic manganese(II) complex of one of these ligands was isolated. Upon exposure to dioxygen, acetonitrile solutions of the complex in the presence of chloride ions lead to the formation of a manganese(IV) complex. The crystal structure of this complex is reported, and it is shown that the metal is in the 4-coordinate ligand site and is bound to two chloride ions.     

新型氮杂大环化合物的研究 1: 取代四吡唑大环化合物的合成及配位性能

本文报道了五种新型四吡唑大环化合物的合成, 探讨了它们对Li^+, Na^+苦味酸盐的CH2Cl2液膜传递性能以及对Ru(Ⅱ)离子的配位作用。实验结果表明, 这类大环配体对两种碱金属离子具有较高的液膜传递速度; 与Ru(Ⅱ)的配合物中除四个吡唑环参与配位外, 另有一分子DMSO和分子H2O从轴向与Ru(Ⅱ)配位, 形成稳定的八面体配位结构。     

Design and Synthesis of Compartmental Ligands and their Complexes for the Production of Catalytic Antibodies

The synthesis and coordination properties of mixed N,O‐compartmental ligands is described. Macrocyclic ligands 8 and 15 were designed to mimic transition‐state analogs for the production of catalytic antibodies for C−H activation reactions. Reaction of 8 with vanadyl cations yields the dinuclear complex 9 , which was characterized by X‐ray crystallography. Amputated ligands 17 and 18 react with various transition‐metal cations to yield complexes designed to act as coenzymes for the catalytic antibodies. The Ni complex of 17 ( 19 ) was also structurally characterized by X‐ray crystallography.     

Chelate complex formation as a basis for titration processes

Metal cations can be looked upon as LEWIS acids and their reaction with ligands during complex formation can be compared to the addition of the proton to a base. The complex formation reactions, however, lack sharp and definite endpoints and metal cations therefore cannot be titrated with ammonia, cyanide and other ligands in the same way as the hydrogen ion can be titrated alkalimetrically. The theoretical reason for this fact is discussed and it is shown that complex formations gain the characteristic properties of neutralisation reactions if the simple ligands are replaced by a polydentate group which is able to satisfy not only one, but several of the coordination points of the metal cation. A great number of titration processes can be based on such reactions.     

Stability constants of metal complexes of macrocyclic ligands with pendant donor groups

Abstract

In our studies of the stability constants of metal complexes, we have investigated a number of macrocyclic ligands with pendant donor groups. The ligands are characterized by the fact that they have nitrogen donors in the macrocyclic ring and oxygen or sulfur donors in the pendant arms. These ligands represent seven different macrocycles, and by varying the pendant donor groups, ten different ligands are indicated. The affinities of these ligands for fifteen metal ions will be described. The Fe(III) complex of triazanonane with o-hydroxypyridyl or o-hydroxybenzyl pendant donor groups are the most stable ferric complexes ever reported. The In(III) complex of triazacyclononane with pendant mercaptoethyl donor groups, is exceptionally stable. Also, the Ca(II) complex of DOTA probably has the highest stability of any calcium(II) complex. These, and other comparisons will be made on the basis of the thermodynamic stability constant data for the ligands described.     

由柔性配体庚二酸组装的微孔稀土配位高聚物

合成了3种新的庚二酸(H₂pim)稀土配位高聚物[Nd(Hpim)(pim)(H₂O)]_n·2nH₂O(1),[RE₂(pim)₃(H₂O)]_n·nH₂O[RE=Er(2),RE=Ho(3)],并通过元素分析红外光谱和单晶X射线衍射技术确定了其组成和晶体结构.配合物1为具有微孔的三维网状结构.配合物2和3同构,通过两种类型的O-H…O氢键将由配位键构筑的二维骨架结构组装成三维超分子结构.在这3个配合物中,庚二酸配体在同一配合物的结构中均存在不同的构象,体现了柔性配体不同于刚性配体的配位特点.     

配合物稳定性与配位体酸碱强度间的直线自由能关系 III:N-(间取代苯基)氨基乙酸的铜(II)、镍(II)配合物稳定性及热力学性质的研究

The stepwise formation constants of complex compounds formed from N-(m-substituted-phenyl) glycines (m-RC6H4NHCH2COOH(m-RPhG), R = H, CH3, CH3O, Cl, NO2) with Cu(II) and Ni(II) were determined by pH method at 15, 25 35`C in 30% (V/V) ethanol solution in the presence of 0.1m NaClO4. Their thermodynamical parameters were calculated. It was found that the N-(m-substituted-phenyl) glycine complexes also showed linear free energy relationships between the stability of complex compounds and the base strength of the ligands just as the para-substituted isomers reported previously. Linear relationships not only existed between their thermodynamical parameters and the base strength of the ligands but also existed between the formation enthalpy of complex compounds and the neutralization enthalpy of the ligands and between the formation entropy of complex compounds and neutralization entropy of the ligands as well.     

Helical binuclear Co complexes of pyriporphyrin analogue for sensing homochiral carboxylic acids

A hybrid macrocycle composed of two bipyridines and two dipyrrins gave biscobalt complexes of figure eight macrocycle conformation with κ²-carboxylate ligands and water ligands at the axial sites. The axial acetate ligands of the biscobalt complex are readily exchanged with carboxylates of α-hydroxyl acids and α-amino acids. The chiral center of the axial carboxylate ligands controls the helical handedness of the macrocycle as evidenced by a typical CD couplet at 550 nm. The substitution labile nature of the biscobalt complex plays a key role for helical chirality induction on the macrocycle upon co-ordination of chiral carboxylate anions.     

Coordination mode for turn-based phosphine ligands: the origin of selectivity in Pd catalysis

A series of experiments was performed to determine the nature of the catalyst in peptide-derived phosphine ligands. The selectivity of the catalyst system was determined with four ligands that are diastereomeric at the phosphine containing amino acid. Additionally, a series of monophosphine ligands was synthesized and screened to determine if the active catalysts are derived from a phosphine-amide complex.     

席夫碱-铝配合物的合成及对丙交酯的立体选择性聚合

设计、 合成了一系列不对称席夫碱配体, 得到了相应的金属铝配合物. 研究了配合物在外消旋丙交酯的开环聚合反应中的催化性能. 结果表明, 系列配合物对外消旋丙交酯(rac-LA)的聚合催化活性明显提高, 并具有立体选择性.     

Selective complexation and transport of europium ions at the interface of vesicles

The aim of the present work was to design functionalized lipidic membranes that can selectively interact with lanthanide ions at the interface and to exploit the interaction between membranes induced by this molecular-recognition process with a view to building up self-assembled vesicles or controlling the permeability of the membrane to lanthanide ions. Amphiphilic molecules bearing a beta-diketone unit as head group were synthesized and incorporated into phospholipidic vesicles. Binding of Eu(III) ions to the amphiphilic ligand can lead to formation of a complex involving ligands of the same vesicle membrane (intravesicular complex) or of two different vesicles (intervesicular complex). The effect of Eu(III) ions on vesicle behavior was studied by complementary techniques such as fluorimetry, light scattering, and electron microscopy. The formation of an intravesicular luminescent Eu/beta-diketone ligand (1/2) complex was demonstrated. The linear increase in the binding constant with increasing concentration of ligands in the membrane revealed a cooperative effect of the ligands distributed in the vesicle membrane. The luminescence of this complex can be exploited to monitor the kinetics of complexation at the interface of the vesicles, as well as ion transport across the membrane. By encapsulation of 2,6-dipicolinic acid (DPA) as a competing ligand which forms a luminescent Eu/DPA complex, the kinetics of ion transport across the membrane could be followed. These functional vesicles were shown to be an efficient system for the selective transport of Eu(III) ions across a membrane with assistance by beta-diketone ligands.