球型Ni(OH)2表面包覆Y(OH)3及其高温充放电性能

应用共沉淀的方法在球型Ni(OH)₂的表面包覆了一层Y(OH)₃,并研究了包覆不同含钇量后的球型Ni(OH)₂的高温充放电性能。研究结果表明:包覆Y(OH)₃的球型Ni(OH)₂具有良好的高温充放电性能。其中1C充放电条件下,包覆量为0.3%的Ni(OH)₂较好,0.2C充放电条件下,包覆量为1%的Ni(OH)₂较好。     

三维超分子[Ni(hmt)2(SCN)2(H2O)2][Ni(SCN)2(H2O)4](H2O)2的自组装,晶体结构及磁性质(hmt=六次甲基四胺)

Compound [Ni(hmt)₂(SCN)₂(H₂O)₂][Ni(SCN)₂(H₂O)₄](H₂O)₂ (hmt=hexamethylenetetramine) was pre-pared and structurally characterized by means of X-ray single crystal diffraction. The two neutral units [Ni(hmt)₂(SCN)₂(H₂O)₂] and [Ni(SCN)₂(H₂O)₄] are joined together through hydrogen bonds N…H-O, O…H-O and S…H-O. In the solid state, the compound has three-dimensional network structure. The determination of its variable-temperature magnetic susceptibilities (5～300K) shows that the magnetic behavior obeys the Curie-Weiss law over the whole temperature ranges.     

以PW9为结构基元构筑的夹心型多金属氧酸盐化合物的合成与晶体结构

通过水热合成方法合成了以夹心多酸阴离子{Ni₄(H₂O)₂(PW₉O₃₄)₂}^10-,乙二胺(en)和Ni(Ⅱ)构筑的夹心型多金属氧酸盐化合物[Ni(en)₂]₂[{Ni(en)₂}{Ni(en)₂H₂O}₂{(PW₉O₃₄)₂Ni₄(H₂O)₂}]·16H₂O(1),采用IR、单晶X-射线衍射法、TG/DTG及循环伏安法对标题化合物进行结构和性质研究。该化合物的夹心多酸阴离子通过[Ni(en)₂]²⁺连接形成一维链,并进一步通过氢键作用形成3D超分子结构。     

以PW9为结构基元构筑的夹心型多金属氧酸盐化合物的合成与晶体结构

通过水热合成方法合成了以夹心多酸阴离子{Ni₄(H₂O)₂(PW₉O₃₄)₂}^10-,乙二胺(en)和Ni(Ⅱ)构筑的夹心型多金属氧酸盐化合物[Ni(en)₂]₂[{Ni(en)₂}{Ni(en)₂H₂O}₂{(PW₉O₃₄)₂Ni₄(H₂O)₂}]·16H₂O(1),采用IR、单晶X-射线衍射法、TG/DTG及循环伏安法对标题化合物进行结构和性质研究。该化合物的夹心多酸阴离子通过[Ni(en)₂]²⁺连接形成一维链,并进一步通过氢键作用形成3D超分子结构。     

洗涤时pH值对纳米级β-Ni(OH)2的团聚程度和电化学性能的影响

Nano-scale nickel hydroxide was prepared by precipitate transformation method in the paper. Effect of rinse pH on the agglomeration degree and electrochemical performance of nano-scale Ni(OH)₂ was investigated. The mea-surement results of XRD and TEM indicate that the prepared nano-scale Ni(OH)₂ is β(Ⅱ)-phase,the grain size is in the rang of 10～50nm,and rinse pH exerts a great influence on the agglomeration degree of nano-scale Ni(OH)₂. The agglomeration of material becomes very obvious when rinse pH=11, and the density of nano-scale Ni(OH)₂ is enhanced obviously.Cyclic voltammetry(CV) and simulate cells experiment show that nano-scale Ni(OH)₂ with suitable agglomeration degree have better electrochemical CV performance than those with ideal disperse Ni(OH)₂ and micron Ni(OH)₂, and its proton diffusion coefficient is also the highest. It can elevate the discharge potential platform and prolongs discharge time, so the utilization ratio of Ni(OH)₂ is raised.     

石墨烯氧化程度对Ni(OH)2赝电容性能的影响

基于密度泛函理论(DFT)设计了一系列不同氧化程度的还原氧化石墨烯片(rGNOs)并研究了其表面的氧化缺陷与吸附的氢氧化镍(Ni(OH)₂)之间的相互作用. 结果发现,rGNOs表面的含氧基团与Ni(OH)₂之间的吸附能与含氧基团的氧化程度相关. 在吸附Ni(OH)₂后,rGNOs的原子间距和电荷分布的变化也都受rGNOs表面的含氧缺陷的氧化程度影响. 理论计算的结果与实验观察的结果一致并能给出合理的解释.我们用简单的恒电位电化学沉积法有效地在rGNOs表面制备了粒径只有5 nm的Ni(OH)₂纳米粒子. 在Ni(OH)₂/rGNOs制备过程中,氧化石墨烯的电化学还原是关键步骤. Ni(OH)₂上吸附的Ni(OH)₂因具有更高的吸附能而使其与在镍膜表面直接吸附的Ni(OH)₂(在5 mV·s^-1下比电容为656 F·g^-1)相比具有更高的比电容值(在5 mV·s^-1下为1591 F·g^-1).rGNOs在吸附Ni(OH)₂后构型和电荷分布的变化导致Ni(OH)₂具有更低的等效串联电阻和更佳的频率响应.Ni(OH)₂/rGNOs优异的赝电容特性表明其有潜力成为新型赝电容器材料.     

颜色可区分的氰桥五边形带经亲铜作用聚集的异金属多形体

水热条件下,环境友好的K₂[Ni(CN)₄]能缓慢水解形成cis-[Ni(CN)₂(H₂O)₄]单元和氰基配体,并进一步与金属铜(Ⅰ)原子组装形成异金属的五边形带。这些五边形带通过亲铜聚集作用形成二维有色的超分子多形体[(CuCN)₂Ni(CN)₂(H₂O)₄](1和2)。研究发现,低温条件下形成了密集态的深蓝色的化合物1,然而高温反应条件形成疏松态的紫色化合物2,这一现象与高温高压的反应条件形成密集态的物质这一规律相违背。结构的进一步分析发现五边形环尺寸的微小改变和二维超分子层间距离的差异是引起这一反常的原因。除此之外,这两个新的化合物也是少见的由亲铜性聚集作用诱导的着色异常的多形体的例子,显示了从深蓝色到紫色的颜色改变。磁性研究证实了平面正方形的[Ni(CN)₄]^2-中的金属镍(Ⅱ)转换成了有着基态自旋S=1的八面体配位几何中心。     

颜色可区分的氰桥五边形带经亲铜作用聚集的异金属多形体

水热条件下,环境友好的K₂[Ni(CN)₄]能缓慢水解形成cis-[Ni(CN)₂(H₂O)₄]单元和氰基配体,并进一步与金属铜(Ⅰ)原子组装形成异金属的五边形带。这些五边形带通过亲铜聚集作用形成二维有色的超分子多形体[(CuCN)₂Ni(CN)₂(H₂O)₄](1和2)。研究发现,低温条件下形成了密集态的深蓝色的化合物1,然而高温反应条件形成疏松态的紫色化合物2,这一现象与高温高压的反应条件形成密集态的物质这一规律相违背。结构的进一步分析发现五边形环尺寸的微小改变和二维超分子层间距离的差异是引起这一反常的原因。除此之外,这两个新的化合物也是少见的由亲铜性聚集作用诱导的着色异常的多形体的例子,显示了从深蓝色到紫色的颜色改变。磁性研究证实了平面正方形的[Ni(CN)₄]^2-中的金属镍(Ⅱ)转换成了有着基态自旋S=1的八面体配位几何中心。     

带有水簇(H2O)4的四氰合镍配合物的合成与磁性研究

一个四氰合镍配合物{[Ni(i-Pr₃TACN)][Ni(CN)₄]}₂·2H₂O(1)通过K₂[Ni(CN)₄]和[NiPr₃TACN]Cl₂自组装的方法合成, 单晶解析表明其配合物中存在一个由4个分子水组成的水簇。4个水分子在一个平面上, 每个水分子即是氢键的给体也是氢键的受体。磁化率测定表明配合物中Ni(Ⅱ)间为反铁磁作用且J值为-1.09 cm^-1.     

草酸根桥联Cr(Ⅲ)-Ni(Ⅱ)配合物的合成和磁性

Two new heteropolynuclear metal complexes ［Ni(phen)₂］₃［Cr(ox)₃］₂·8H₂O(1) and ［Ni(bipy)₂］₂［Cr(ox)₃］NO₃·4H₂O(2)(phen=1,10-phenanthroline, ox=oxalato, bipy=2,2-bipyridine) have been synthesized and characterized by elemental analyses, IR, TG-DTA and diffuse reflectance UV-VIS spectra. The temperature dependence of the magnetic susceptibilities of the complexes have been studied over the range 73.6～300K. The results show that ferromagnetic spin exchange interaction exist between Cr(Ⅲ) and Ni(Ⅱ) in the complex (1). The magnetic property of the complex(2) abides Curie law.     

改型镍体系催化丁二烯顺1,4-聚合活性中心价态的研究

改型镍系Ni(naph)_2-Al(i-Bu)_2OC_8H_(17)-BF_3·OEt_2的电子顺磁共振谱指出,活性中心主要由Ni(Ⅰ)组成,预混丁二烯能稳定Ni(Ⅰ)和缩短聚合反应的诱导期,但不改变聚合反应的表观活化能。     

Metallacyclic mechanism of the addition polymerization of norbornene involving Ni(I) and Ni(III) complexes

The catalytic system Ni(COD)₂/BF₃·OEt₂ is highly active in the addition polymerization of nor-bornene (NB). Its activity, which is up to 1930 (kg NB) (mol Ni)⁻¹ h⁻¹, is higher than the activity of the other known nickel complex catalysts. Another advantage of this system over the latter is that it contains a smaller proportion of a Lewis acid (5 molar parts or below) and no conventional stabilizing organoelement ligands. The activity of this system in NB polymerization has been investigated by Fourier-transform IR spectroscopy. According to EPR data, NB polymerization is accompanied by the formation of low-spin complexes of trivalent nickel, which result from the oxidative addition of the monomer to univalent nickel complexes. A metallacyclic mechanism involving Ni(I) and Ni(III) complexes is suggested for NB polymerization.     

新型镍催化体系合成Cis-1,4聚丁二烯的研究

本文研究了以加氢汽油为溶剂的Ni(Naph)_2-Al(i-Bu)_2OR-BP_3·OEt_2及Ni(NaPh)_2-Al(i-Bu)_2OAr-BF3·OEt_2两体系对丁二烯的催化聚合活性、聚合物分子量、微观结构等。各种Al(i-Bu)_2OR或Al(i-Bu)_2OAr为助催化剂组成的新型镍催化体系对丁二烯聚合都有较高的催化活性,所得聚合物Cis-1,4含量在96％以上。磁化率和紫外可见光谱研究证明,在Al(i-Bu)_2OR体系中以Ni(Ⅰ)为主及小量未还原的Ni(Ⅱ);Al(i-Bu)_2OAr中Ni(Ⅰ)及Ni(O)共存。     

Combined polymerization catalysis of nickel complex and zirconocene for branched polyethylene

The polymerization behavior of 2-(2′-pyridyl) quinoxaline nickel dibromide/Cp₂ZrCl₂/MAO system was investigated in three ways: the Ni catalyst was added first, followed by addition of Zr catalyst (method I); the Ni and Zr catalysts were added simultaneously (method II); and the Zr catalyst was added first, followed by addition of Ni catalyst (method III). Results of GC-MS, GPC,¹³C NMR and DSC investigations indicated that the properties of resulting polyethylene were greatly varied by changing feeding orders of the two catalysts. Decreasing Ni/Zr molar ratio or increasing polymerization temperature gave corresponding polyethylenes with less branches and higher melting point. Compared to the procedure using Cp₂ZrCl₂ catalyst only, the activity of Zr catalyst in those combined system decreased because of the competition of ethylene between the [Ni−C] and [Zr−C] active centers. In addition, other zirconocenes were also employed as copolymerization catalysts in the combined system with nickel complex. compared to Cp₂ZrCl₂ case, the ethyl-bridged Zr catalyst performed better for polymerization of ethylene while the Si-bridged Zr catalyst showed better copolymerization ability.     

Polymerization and copolymerization of 2-phthalimidomethyl 1,3-butadiene. I. Preliminary studies of free radical polymerization and polymerizations initiated by various transition metal allyl complexes

2-Phthalimidomethyl 1,3-butadiene was homopolymerized and copolymerized with butadiene by free radical initiators; r₁ and r₂ were close to 1. All the attempts to polymerize 2PMB anionically have been unsuccessful. Preliminary studies of various η³-allylic catalysts showed that η³-allyl M₀(CO)₃OOCCF₃ initiates the polymerization of butadiene and is not sensitive to N-methyl phthalimide (NMP); neither does it initiate the copolymerization of butadiene and 2PMB. On the other hand, a catalyst that results from the reaction of allyl trifluoroacetate with nickel tetracarbonyl is efficient for the copolymerization of butadiene and 2PMB. η³-Allyl nickel trifluoroacetate was prepared in heptane or benzene and used in benzene or methylene chloride. In all cases it initiated the copolymerization of butadiene with 2PMB     

SILICA-SUPPORTED NICKEL AND ZIRCONIUM CATALYSTS FOR BRANCHED POLYETHYLENE*

8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp_2ZrCl_2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis, as well as theCp_2ZrCl_2 and nickel combination system. With decreasing amount of Ni catalyst in the supported catalyst, the molecular chains of oligomers in the resulting solution became shorter, while α-olefin selectivity increased.     

New neutral Ni(II)- and Pd(II)-based initiators for polymerization of styrene

Neutral nickel and palladium σ-acetylide complexes [Ni(CCPh)₂(PBu₃)₂] and [Pd(CCPh)₂(PBu₃)₂] are novel initiators for the polymerization of styrene in CHCl₃ over a range of polymerization temperature from 40 to 60 °C. Between them, the nickel catalyst exhibited much higher activity than the palladium catalyst. The polystyrene obtained with Ni(II) initiator was a syndio-rich atactic polymer and its weight-average molecular weight reached 279 000. The mechanism of the polymerization was discussed and a radical mechanism was proposed.     

Facile synthesis of a tricyclohexylphosphine‐stabilized η3‐allyl‐carboxylato Ni(II) complex and its relevance in electrochemical butadiene carbon dioxide coupling

With the reaction of bis(1,5‐cyclooctadiene)nickel(0) and trans‐penta‐2,4‐dienoic acid in the presence of tricyclohexylphosphine, a new more general method was developed to synthesize cyclic π³‐allyl‐carboxylato Ni(II) complexes, which are known to be intermediates in the C? C coupling of butadiene and CO₂. The cyclic π³‐allyl‐carboxylato Ni(II) complex obtained is tested as a mediator in the electrochemical coupling reaction of butadiene and carbon dioxide. We also demonstrate the dependency on the coordination sphere by using platinum instead of nickel as the metal center. Copyright © 2005 John Wiley & Sons, Ltd.     

BF3·OEt2在镍体系催化丁二烯聚合中的作用

本文借助于紫外可见光谱、磁化率法和聚合活性测定等方法,研究了BF₃·OEt₂在镍体系催化丁二烯聚合中的作用。初步探明了BF₃·OEt₂与Ni(naph)₂作用会形成“F-B-Ni”配合物,对形成活性中心不利。     

Influence of the order of introduction of protonic acids on the formation of active complexes in the Ni(PPh3)4/BF3 · OEt2 catalytic system

The influence of the order of introduction of promoters (complex protonic acids) on the formation of active complexes in the Ni(PPh₃)₄/BF₃ · OEt₂ catalytic system and the activity of these systems in ethylene oligomerization have been studied. The activity of the systems in which nickel exists mainly as cationic Ni(I) complexes is more than one order of magnitude higher than the activity of the systems where nickel exists mainly in the form of Ni(II) hydride complexes. The role of alcohols as promoters in the Ni(PPh₃)₄/BF₃ · OEt₂ catalytic system is elucidated. The alcohols are the source of Ni(II) hydrides and, more importantly, the source of strong Brønsted acids, which efficiently ensure the coordinative unsaturation of the cationic Ni(I) complexes.