Thermal Studies on Solid Complexes of Saccharin with Divalent Transition Metal Ions

The thermal decompositions of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of saccharin were studied in static air atmosphere. All of the complexes contain four molecules of coordination water and two molecules of crystallization water. The water molecules were removed in a single stage, except from the Zn(II) complex, which exhibited two endothermic effects. The dehydration process was usually accompanied by a sharp colour change. The anhydrous complexes exhibited a phase transition and the decomposition or combustion of saccharin occurred in the second and subsequent stages. The final decomposition products were identified by XRPD as the respective metal oxides. The kinetic parameters, such as the order of reaction and energy of activation for the dehydration stage, were evaluated and the thermal stabilities of the complexes are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Studies on Solid Complexes of Uracil With Some Divalent Transition Metal Ions

The thermal behaviour of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pd(II) complexes of uracil was studied by TG, DTG and DTA in a dynamic nitrogen atmosphere. Two processes occur in the isolated uracil complexes: dehydration and pyrolytic decomposition. In the hydrated complexes, the first stage observed was the loss of water molecules, which was followed by decomposition of the uracil. The thermal dehydration of the complexes occurred in from one to three steps. The final decomposition products were found to be the respective metal oxides, except in the cases of the Co(II) and Pd(II) complexes, which produced metallic cobalt and palladium, respectively. The order of reaction and energy of activation for the dehydration stage were evaluated.This revised version was published online in November 2005 with corrections to the Cover Date.     

过渡金属络合物催化乙烯齐聚

综述了乙烯齐聚的最新成果,重点阐述了用于乙烯齐聚的新型催化剂,讨论了烯烃高聚与齐聚催化剂的关系,烯烃高聚与齐聚的反应机理相同,。差别主要在于烯烃插入与β－H消除反应的速率,第IV副族金属络合物主要催化乙烯齐聚,第Ⅲ副族金属主要催化乙烯高聚,改变茂金属催化体系的助催化剂和反应条件可得到齐聚产物,选择体积较小配体的第Ⅷ族金属络合物,有利于β－H消除得到齐聚产物。     

过渡金属配合物催化的二氧化碳的固定*

综述了利用过渡金属配合物和二氧化碳的配位及插入反应实现二氧化碳固定的基本方法、原理及其研究现状。     

Gas Chromatography of Transition Metal Salicylaldimine Complexes

Abstract

The stability and ease of formation of some neutral salicylaldimine transition metal complexes has suggested that they may be gas chromatographed and find analytical applications. Thermal an of some bidentate Ni(II), Cu(II) and Zn(II) salicylaldimine comp has shown them to be thermally stable and volatile. Observations the gas chromatographic separation of some of these chelates is described, their favorable properties allow elution from glass a stainless steel columns with minimal decomposition under favorable conditions.     

过渡金属配合物催化炔烃和亲核试剂的羰化反应

羰化反应(氢甲酰化反应、羰化羧酸化反应、羰化酯化反应、羰化酰胺化反应等)是制备醛(/醇)、羧酸、羧酸酯、酰胺等高附加值含氧羰基化合物有效的途径,具有反应原子经济性高、目标羰基化合物选择性高、反应条件较氧化过程更温和可控的优势.羰化反应的原料包括烯烃、炔烃、卤代烃、醇等有机化合物.其中,在过渡金属催化剂作用下,炔烃与不同...     

Thermal Decomposition of Chloromethylated Poly(styrene)-PAN Resin and Its Complexes with Some Transition Metal Ions

The complexes formed by the chemically modified chloromethylated poly(styrene)-PAN (CMPS-PAN) as a resin chelating ion exchanger were characterized by infrared and potentiometry. The thermal degradation of pure CMPS-PAN resin and its complexes with Au³⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺ and Pt⁴⁺ in air atmosphere has been studied using thermal gravimetry (TG) and derivative thermal gravimetry (DTG). The results showed that four different steps accompany the decomposition of CMPS-PAN resin and its complexes with the metal ions. These stages were affected by the presence of the investigated metal ions. The thermal degradation of CMPS-PAN resin in the presence of the ions showed different stability of the resin in the following decreasing order: Au³⁺>Pt⁴⁺>Mn²⁺>Cu²⁺>Cr³⁺>Fe³⁺. On the basis of the applicability of a non-isothermal kinetic equation, the decomposition process was a first-order reaction. The activation energy, Ea, the entropy change, ΔS ^*, the enthalpy change, ΔH ^* and the Gibbs free energy of activation, ΔG ^* were calculated by applying the theory of the reaction rates. The effect of the different central metal ions on the calculated thermodynamic activation parameters was discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Prospects of Metal Complexes Peripherally Substituted with Sugars in Biomedicinal Applications

Sugar is good for you! The latest developments in the field of sugar substitution of metal complexes and its influence on the action of these complexes in biological systems are discussed (see figure). In particular, the progress in applications as selective tracers and therapeutics in connection to the underlying chemical structure is highlighted.

     

氮配位过渡金属配合物在硅氢加成反应中的应用研究

氮配位过渡金属配合物在近十几年来得到迅速的发展。 通过设计不同的含氮配体与不同过渡金属进行配位形成的氮配位过渡金属配合物,在硅氢加成反应中有很大应用研究价值。本文综述了氮配位铑、铁、铼、钴、锌等过渡金属配合物在酮或者烯烃的硅氢加成反应中的新进展。二 NFDA1 唑啉及二氢吡咯等含氮配体的优化设计必将大大促进含氮铁、铼、钴配合物在酮或者亚胺的硅氢加成反应中的应用。     

三核过渡金属配合物在催化反应中的研究进展

多核过渡金属配合物作为一类广泛应用的均相催化剂,其设计灵感往往来自天然酶的多金属活性位点所发挥的重要作用.目前,三核金属配合物作为活化小分子的多金属催化剂受到了广泛的关注.为深入理解三核过渡金属配合物在催化反应中作用特点,对近年报道的代表性三核过渡金属配合物按金属中心进行分类,并对配体环境形成特点及催化应用进行综述.从金属中心出发,讨论了三核过渡金属配合物的几何结构和电子特征;从配体环境出发,总结了关联三个独立的金属位点的配位环境特征;在催化应用方面,重点综述了三核过渡金属配合物在涉及特定化学键活化反应的催化作用机制,最后对三核过渡金属配合物的催化应用前景进行展望.     

Calix[4]arene stabilized Transition Metal Imido Complexes

The usage of calix[n]arenes as ancillary poly(phenolate) ligands is a rapidly developing area in coordination chemistry. This article focuses on the synthesis, structure and reactivity of calix[4]arene‐ and calix[4]arene ether‐stabilized imido complexes of group 4 — 6 transition metals as well as on the comparison of calix[4]arene dialkyl ethers in particular with other widely employed related ligand systems such as salenes, porphyrins and tetraazaannulenes. Contrary to these nitrogen containing systems, it is much easier to control the charge of the ligand system through the degree of alkylation of the calixarene's lower rim without a major change in the geometry of the resulting metal complex. This could lead to isoelectronic and structurally closely related transition metal complex fragments for metals in neighboring groups of the periodic table or for metals in different oxidation states. The “intrinsic” reactivity of metal imido linkages might therefore be explored using calix[4]arenes and calix[4]arene ethers and first results are summarized in this research report.     

Hydrosilylation Of Heterocyclic Aldimines Catalyzed By Transition Metal Complexes

The addition of triethylsilane to O- and S- heterocyclic Schiff bases in the presence of Rh, Pd, Pt, and Ir complexes has been studied. A series of the corresponding amines has been synthesized using the most active catalysts, which were the dimeric, monovalent complexes [Rh(1,5-cyclooctadiene)Cl]₂ and [Pd(allyl)Cl]₂.     

Asymmetric Epoxidation of Non-Functionalized Alkenes Using Transition Metal Complexes

Asymmetric catalytic epoxidation of alkenes such as styrenes, chromenes and indene using transition metal complexes both inhomogeneous and heterogeneous phase has been discussed in this review. The various strategies to make the catalysts recyclable by introducing in-built phase transfer ability, converting these to dimeric form, exchanging into clays and supporting on polymeric or inorganic supports are discussed at length.     

Mild and Complete Carbonyl Ligand Scission on a Mononuclear Transition Metal Complex

The complete scission of the carbon–oxygen bond of carbon monoxide, while frequently observed on bulk metals and with bimetallic and cluster transition metal complexes, is unknown with monometallic systems. Reaction of a zerovalent iron bis(borylene) complex with a cyclic (alkyl)(amino)carbene revealed a highly selective intramolecular cleavage of the C?O bond of a carbonyl ligand at room temperature, leading to the formation of a highly unusual iron complex containing a base‐stabilized (bora)alkylideneborane ligand. DFT investigation of the reaction mechanism suggested that the two Lewis acidic borylene boron atoms cooperate to cleave the C?O multiple bond.     

Bioactive Luminescent Transition‐Metal Complexes for Biomedical Applications

The serendipitous discovery of the anticancer drug cisplatin cemented medicinal inorganic chemistry as an independent discipline in the 1960s. Luminescent metal complexes have subsequently been widely applied for sensing, bio‐imaging, and in organic light‐emitting diode applications. Transition‐metal complexes possess a variety of advantages that make them suitable as therapeutics and as luminescent probes for biomolecules. It is thus highly desirable to develop new luminescent metal complexes that either interact with DNA through different binding modes or target alternative cellular machinery such as proteins as well as to provide a more effective means of monitoring disease progression. In this Review, we highlight recent examples of biologically active luminescent metal complexes that can target and probe a specific biomolecule, and offer insights into the future potential of these compounds for the investigation and treatment of human diseases.     

Insight of the Metal–Ligand Interaction in f-Element Complexes by Paramagnetic NMR Spectroscopy

The magnetic properties of Ln^III and An^III complexes formed with dipicolinate ligands have been studied by NMR spectroscopy. To know precisely the geometries of these complexes, a crystallographic study by single-crystal X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) in solution was performed. Several methods to separate the paramagnetic shifts observed in the NMR spectra were applied to these complexes. Methods using a number of nuclei of the dipicolinate ligands revealed an abrupt change in the geometries of the complexes and a metal–ligand interaction in the middle of the lanthanide series. A study of the variation of the paramagnetic shifts with temperature demonstrated that higher-order terms of the dipolar and contact contributions are required, especially for the lightest Ln^III and almost all the studied An^III. Bleaney's parameters <S_z>_a and relating to the contact and dipolar terms, respectively, were deduced from experimental data and compared with the results of ab initio calculations. Quite a good agreement was found for the temperature dependencies of <S_z>_a and . However, the values obtained from cation magnetic anisotropy calculations showed some discrepancies with the values derived from Bleaney's equation defined for Ln^III. Other parameters, such as the crystal field parameter and the hyperfine constants F_i obtained from the experimental data of the [An(ethyl-dpa)₃]³⁻ complexes (ethyl-dpa=4-ethyl-2,6-dipicolinic acid), are at odds with the assumptions underlying Bleaney's theory.     

N‐Heterocyclic Carbene–Phosphinidyne Transition Metal Complexes

The N‐heterocyclic carbene–phosphinidene adduct IPr?PSiMe₃ is introduced as a synthon for the preparation of terminal carbene–phosphinidyne transition metal complexes of the type [(IPr?P)ML_n] (ML_n=(η⁶‐p‐cymene)RuCl) and (η⁵‐C₅Me₅)RhCl). Their spectroscopic and structural characteristics, namely low‐field ³¹P NMR chemical shifts and short metal–phosphorus bonds, show their similarity with arylphosphinidene complexes. The formally mononegative IPr?P ligand is also capable of bridging two or three metal atoms as demonstrated by the preparation of bi‐ and trimetallic RuAu, RhAu, Rh₂, and Rh₂Au complexes.     

Magnetocaloric Properties of Heterometallic 3d–Gd Complexes Based on the [Gd(oda)3]3− Metalloligand

A series of heterometallic 3d–Gd³⁺ complexes based on a lanthanide metalloligand, [M(H₂O)₆][Gd(oda)₃] ? 3 H₂O [M=Cr³⁺ ( 1‐Cr )] (H₂oda=2,2′‐oxydiacetic acid), [M(H₂O)₆][MGd(oda)₃]₂ ? 3 H₂O [M=Mn²⁺ ( 2‐Mn ), Fe²⁺ ( 2‐Fe ) and Co²⁺ ( 2‐Co )], and [M₃Gd₂(oda)₆(H₂O)₆] ? 12 H₂O [M=Ni²⁺ ( 3‐Ni ), Cu²⁺ ( 3‐Cu ), and Zn²⁺ ( 3‐Zn )], are reported. Magnetic and heat‐capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of ?ΔS_m between complexes 2‐Co and 1‐Cr . In these two complexes, the 3d metal ions have the same spin (S=3/2 for Co²⁺ and Cr³⁺ ions), and the theoretical calculation suggested a larger ?ΔS_m value for 2‐Co (47.8 J K^?1 kg^?1) than 1‐Cr (37.5 J K^?1 kg^?1); however, the significant anisotropy of Co²⁺ ions in 2‐Co , which can result in smaller effective spins, gives a smaller value of ?ΔS_m for 2‐Co (32.2 J K^?1 kg^?1) than for 1‐Cr (35.4 J K^?1 kg^?1) at ΔH=9 T.