Borane Activators for Late‐Transition Metal Catalysts in Norbornene Polymerization

Nickel(II) and palladium(II) complexes of the general type [MCl₂{Ph₂P(CH₂)_nPPh₂}] with n = 2, 3 and M = Ni ( 2 , 3 ), Pd ( 4 , 5 ) have been utilized as catalysts for the polymerization reaction of norbornene. It was found that the use of B(C₆F₅)₃/triethylaluminium (TEA) in comparison to methylaluminoxane as an activator towards complexes 2 , 3 and 5 gave comparable polymerization activities, and the system 4 /B(C₆F₅)₃/TEA even led to an extremely high polymerization activity of 10⁷ g_polymer/mol_metal· h.     

后过渡金属催化降冰片烯加成聚合

综述了后过渡金属催化剂催化降冰片烯加成聚合的研究进展。主要介绍了Ni、Pd、Co三种金属催化剂各自的结构以及其催化降冰片烯聚合的特点,同时也阐述了Ni、Pd催化剂催化降冰片烯聚合的机理。     

新型烯烃聚合催化剂研究进展

由于过渡金属催化剂在烯烃聚合方面具有高活性和良好的分子剪裁性,通过调节催化剂的微结构或温度、压力等聚合环境的变化,可以在分子层次上实现烯烃聚合物的分子设计与组装,实现聚合物物理性质的调控,最近引起了人们的广泛关注。本文介绍了过渡金属催化剂的合成及其负载化,水相烯烃聚合及活性聚合等方面的研究进展。     

Polymerization of 4-Dimethylamino-N-propargylpyridinium Bromide by Transition Metal Catalysts

The polymerization of an ionic propargyl derivative, 4-dimethylamino-N-propargylpyridinium bromide (DMAPPB), was carried out by palladium, platinum, and ruthenium chlorides. The polymerization of DMAPPB by these transition metal catalysts proceeded well to give a relatively high polymer yield. The chemical structure of the resulting polymer was characterized by such instrumental methods as elemental analysis, infrared, NMR, UV–visible spectroscopies to have conjugated polymer backbone system bearing 4-dimethylamino-N-methylenepyridinium bromide. The polymer was soluble in DMF, DMSO, and formic acid, and found to be less hygroscopic than those of similar homologues having more smaller substituents. The resulting polymers were mostly black powders and showed the amorphous morphology.     

过渡金属钯催化的炔烃羰基化反应新进展

主要综述了过渡金属钯催化的炔烃羰基化反应最新研究进展     

Transition Metal Catalysts in the Synthesis of Functionalized Substituted Phosphonates

Abstract

Synthesis of new functionalized phosphonates was achieved by two ways, using either nucleophilic or electrophilic modification of organophosphorus compounds by transition metal catalytic reactions The first way employs the transformation of carbonyl group in α, β, and y-ketophosphonates by nucleophilic addition (silacyanation, hydrosilylation, etc).     

Phase‐Transfer Activation of Transition Metal Catalysts

With metal‐based catalysts, it is quite common that a ligand (L) must first dissociate from a catalyst precursor (L′_nM?L) to activate the catalyst. The resulting coordinatively unsaturated active species (L′_nM) can either back react with the ligand in a k_?1 step, or combine with the substrate in a k₂ step. When dissociation is not rate determining and k_?1[L] is greater than or comparable to k₂[substrate], this slows the rate of reaction. By introducing a phase label onto the ligand L and providing a suitable orthogonal liquid or solid phase, dramatic rate accelerations can be achieved. This phenomenon is termed “phase‐transfer activation”. In this Concept, some historical antecedents are reviewed, followed by successful applications involving fluorous/organic and aqueous/organic liquid/liquid biphasic catalysis, and liquid/solid biphasic catalysis. Variants that include a chemical trap for the phase‐labeled ligands are also described.     

新型后过滤金属烯烃聚合催化剂——镍系烯烃聚合催化剂

镍系烯烃聚合催化剂是近年来受到广泛关注的一类新型催化剂，是配位催化研究的热点之一。这类催化剂具有高催化活性、单活性中心和良好的分子剪栽性，可以在分子层次上实现烯烃聚合的分子设计与组装。本文介绍了镍系烯烃聚合催化剂的发展和研究概况，并评述了聚合特性及最新研究进展。     

新型后过渡金属烯烃聚合催化剂－－镍系烯烃聚合催化剂*

镍系烯烃聚合催化剂是近年来受到广泛关注的一类新型催化剂,是配位催化研究的热点之一。这类催化剂具有高催化活性、单活性中心和良好的分子剪栽性,可以在分子层次上实现烯烃聚合的分子设计与组装。本文介绍了镍系烯烃聚合催化剂的发展和研究概况,并评述了聚合特性及最新研究进展。     

Polymerization of 1-Ethynyl-1-Cyclohexanol by Transition Metal Catalysts

Abstract

The polymerization of 1-ethynyl-l-cyclohexanol (ECHO) was carried out by various transition metal catalysts. The Mo- and W-based catalysts gave a relatively low yield of polymer (≤32%). The catalytic activity of Mo-based catalysts was greater than that of W-based catalysts. PdCl₂ was a very effective catalyst for the present polymerization and gave a high yield of polymer. (Ph₃P)₂PdCl₂ and PtCl₂ were also found to be effective catalysts. The structure of the resulting poly(ECHO) was identified by various instrumental methods as a conjugated polyene structure having an α-hydroxycyclohexyl substituent. The poly(ECHO)s were mostly light-brown powders and completely soluble in various organic solvents such as chloroform, chlorobenzene, benzene, DMSO, and THF. Thermal and morphological properties were also studied.     

过渡金属乙烯齐聚与聚合催化剂研究进展

综述了近年来过渡金属配合物催化乙烯齐聚与聚合的最新进展;介绍了乙烯齐聚或聚合的反应时间、反应温度、乙烯压力、助催化剂用量等反应条件及配体上不同取代基对前过渡金属(铬,锆,钛,钒)和后过渡金属(铁,钴,镍,铜)配合物的催化活性和齐聚或聚合产物的影响;分别以钛和镍配合物催化剂为例,介绍了前过渡金属和后过渡金属催化乙烯齐聚或聚合的机理。     

Diamino‐Substituted Carbene Transfer between Transition Metal Ions

Diamino‐carbene ligand transfer between various metalions is studied, particularly with Pd (II) to Rh(I), Rh(I) to Au(I). Reactions of various carbene complexes with AgPF₆ result in the cleavage of the M=C bond to give the protonated carbene species, imidazolidin‐2‐ylidinium salt, indicating the presence of free carbene ligand in the reaction medium. When the carbene transfer process was carried out in tetrahydrofuran, the polymerization of tetrahydrofuran occurred.     

后过渡金属烯烃聚合催化剂的研究进展

综述了近两年来后过渡金属(VIII族)催化剂在乙烯、丙烯和α-烯烃聚合,α-烯烃和极性单体共聚,α-烯烃活性聚合,以及乙烯齐聚等方面的最新进展.     

Building from Ga‐Porphyrins: Synthesis of Ga‐Acetylide Complexes Using Acetylenes and Polyynes

Multidimensional, conjugated building blocks have been formed through the axial coordination of polyynes to the central Ga atom of tetraarylporphyrins. Electron deficient pentafluorophenyl substituents in the meso‐positions provide more stable σ‐acetylide complexes to Ga than analogous structures with tert‐butylphenyl groups. Mono‐, di‐, and triynes have been used, including a pyridyl endcapped diyne that allows for formation of porphyrin triads through coordination of the pyridyl ligand to a Ru porphyrin.     

Asymmetric Transfer and Pressure Hydrogenation with Earth‐Abundant Transition Metal Catalysts

The asymmetric transfer and pressure hydrogenation of various unsaturated substrates provides a succinct pathway to important chiral intermediates and products such as chiral alcohols, amines, and alkanes. The use of earth‐abundant transition metals such as Fe, Co, Ni, and Cu in hydrogenation reactions provides an attractive alternative to traditionally used metals such as Ru, Rh, Ir, and Pd because they are comparatively inexpensive, less toxic, and as their name suggests, more abundant in nature. Earth‐abundant transition metal‐catalyzed asymmetric hydrogenation is rapidly becoming an important area of research. This review summarizes advances in the asymmetric hydrogenation of unsaturated bonds (ketones, imines, and alkenes) with earth‐abundant transition metals.     

Cyclooligomerization with Transition Metal Catalysts

This report is concerned not only with the syntheses of new ring systems and the preparation of derivatives of known rings but also with new types of catalysts based upon, e. g., nickel, iron, molybdenum, manganese, and palladium. The broad applicability of the methylene insertion reaction as a method for identifying mono- and di-methyl-substituted eight-, ten-, and twelve-membered rings is also demonstrated. A further section is concerned with the possible mechanism of C? C bond formation in transition metal complexes; several earlier suggestions have been revised in the light of new experimental data. In addition, experimental results are discussed which indicate that the reactivity and selectivity of the complexes formed by the nickel-ligand catalyst and olefins or alkynes depend upon the structure of the ligands.