四磺化酞菁钴轴向配位反应研究

采用分光光度法研究了四磺化酞菁钴(CoTSPc)与配体L(L=en,NH₃,CN^-)的配位反应,研究了配位反应动力学,测定了配合物的稳定常数K,并讨论了配位反应机理。研究表明:CoTSPc与L形成CoTSPc(L)₂的配合物,动力学方程为:-dC_M/dt=kC_MC_Lⁿ,C_M、C_L分别为CoTSPc的单体和配体的浓度(en:n=1;NH₃,CN^-:n=2);CoTSPc(L)₂的稳定常数为:L=en,lgK=4.639;L=NH₃,lgK=5.328;L=CN^-,lgK=9.116.     

基于氧化还原反应的配位平衡移动总反应平衡常数的推导

配位平衡的移动,可以遵从相同的“推导总反应的平衡常数”模式来做定性和定量的探讨。但在“氧化还原反应对配位平衡的影响”中,只是对化学反应做定性描述,总反应的平衡常数并没有推导,缺乏定量的探讨。原因在于氧化还原平衡常数与其他3大平衡常数不同,无法直接查得,需借助公式算出,具有隐蔽性,给总反应的推导造成了障碍。本文通过总反应平衡常数的推导解决了这个问题。     

八乙基金属卟啉的轴向配位反应研究及稳定常数测定

测定了八乙基金属卟啉 (OEP) M中当M=Zn, Cu, FeCl 或 MnCl时在CH2Cl2, N,N-二甲基甲酰胺(DMF), 二甲亚砜(DMSO), 吡啶(Py)等4种不同非水溶剂中的紫外-可见光谱, 探讨了溶剂的性质对八乙基金属卟啉光谱的影响. 结果表明八乙基锌、铁、锰卟啉在CH2Cl2中能够与配位溶剂如DMF, DMSO或pyridine 等发生轴向配位反应生成五配位或六配位的金属卟啉配合物. 用微量光谱滴定法测定了Zn、 Fe、 Mn等金属卟啉和配位溶剂发生轴向配位反应的稳定常数(logK). 讨论了中心金属离子的电负性以及配位溶剂的给电子能力对稳定常数的影响.     

Pd（Ⅱ）与α－氨基肟配体PnAO配位反应的动力学研究

本文用紫外可见分光光度法研究了Ｐｄ（Ⅱ）与ＰｎＡＯ生成配合物的反应动力学，测得了几个温度下的反应表观速率常数，提出了一个由螯合作用促进的多步反应机理，计算求得了速率控制步骤的反应速率常数和该步的活化参数，△Ｈ≠＝５７．５７ｋＪ·ｍｏｌ－１，△Ｓ≠＝－３４．２４Ｊ·ｍｏｌ－１·Ｋ－１。讨论了介质酸度和离子强度对反应速率的影响．     

八乙基金属卟啉的轴向配位反应及热力学常数测定

利用微量光谱滴定法研究了八乙基锌、铁、锰卟啉与N,N′-二甲基甲酰胺(DMF)、二甲基亚砜(DMSO)、吡啶(Py)等碱性溶剂在CH2Cl2中的轴向配位反应。结果表明在给定的溶液中反应生成了五配位或六配位的配合物。测定了在不同温度下(283～298K)配位反应的平衡常数(logβn)以及焓变(△r Hθm)、熵变(△r Sθm)和吉布斯自由能变(△r Gθm)等热力学常数,讨论了配位溶剂、中心金属离子以及温度等对平衡常数和热力学常数的影响。     

Cu(Ⅱ)与α-氨基肟配体PnAO配位反应的热力学及热化学研究

用pH法测定了PnAO的质子化常数及Cu(Ⅱ)-PnAO,Cu(Ⅱ)-5-R-Phen-PnAO配合物的稳定常数.用直接量热法测定了PnAO的质子化热及Cu(Ⅱ)二元,三元配合物的生成热.Cu(Ⅱ)三元配合物体系与5-R-Phen的质子化体系之间存在线性热力学函数关系.并对取代基效应作了解释     

HPLC法测定某些高铼酸盐易变配位化合物的稳定常数

根据用柠檬酸盐作流动相时,ReO_4~-在PRP-S柱上保留时间出现异常现象,本文提出用HPLC法测定高铼酸根与柠檬酸、酒石酸和草酸形成的易变配位化合物的稳定常数,在水溶液中分别为123、35.6和45.1。     

基于MX_4结构的配位化合物析氢反应催化性能

具有MX4结构的(M=Fe,Co,Ni,Cu等,X=N,S,Se等)小分子配位化合物及配位聚合物(MX4催化剂),由于其新颖的结构和优异的电催化析氢性能受到研究人员越来越多的关注。本文综述了MX4催化剂的研究进展,其中MX4催化剂活性受金属中心、配位原子、配体的结构以及材料的形貌、尺寸等因素的影响。理论计算有助于分析催化剂中这些因素对催化剂活性的影响,也有助于通过理论模拟,设计更合理的催化剂分子结构。     

含有配位基团的芳基汞化合物的金属转移反应

本文综述了含有配位基团芳基汞化合物与过渡金属和非过渡金属之间的金属转移反应。讨论了底物中的配位基团对于某些金属转移产物形成的影响.     

Quantitative Description of Polymerization Reactions by Means of Multiparameter Equations

Linear free energy relations are successfully extended to the principle of polylinearity when propagation is the predominant rate-determining step and others (e.g., initiation, termination) can be neglected. The cationic polymerization of vinyl ethers and p-substituted styrenes provides improved insight into the mechanism. On the other hand, the overall rate of the homopolymerization or the relative reactivity of the cross-propagation step in copolymerization can be controlled by means of multi-parameter equations. Some examples are given where multi-parameter correlation analysis with rather empirical parameters are shown useful for controlling industrial processes as well as for definite product formation.     

Cascade Reactions in Quantitative Solid-State Syntheses

100 % yield in the absence of the liquid phase : A one-pot synthesis of highly substituted pyrroles, which proceeds in solution with moderate yields, functions quantitatively in the solid–solid variant, and that at much lower temperatures, although at least four reaction steps are required. The reaction execution in the absence of liquid phases avoids product workup because of the 100 % yield and is thus resource-saving and environmentally friendly.     

Crystallographic and Spectroscopic Investigations on Oxidative Coordination in the Heteroleptic Mononuclear Complex of Cerium and Benzoxazine Dimer

Among lanthanide-based compounds, cerium compounds exhibit a significant role in a variety of research fields due to their distinct tetravalency, high economic feasibility, and high stability of Ce(IV) complexes. Herein, a systematic investigation of crystallographic information, chemical properties, and mechanistic formation of the novel Ce(IV) complex synthesized from cerium(III) nitrate hexahydrate and 2,2′-(methylazanediyl)bis(methylene)bis(4-methylphenol) (MMD) ligand has been explored. According to the analysis of the crystallographic information, the obtained complex crystal consists of the Ce(IV) center coordinated with two nitrate ligands and two bidentate coordinated (N-protonated and O,O-deprotonated) MMD ligands. The fingerprint plots and the Hirshfeld surface analyses suggest that the C–H⋯O and C–H⋯π interactions significantly contribute to the crystal packing. The C–H⋯O and C–H⋯π contacts link the molecules into infinite molecular chains propagating along the [100] and [010] directions. Synchrotron powder X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) techniques have been employed to gain an understanding of the oxidative complexation of Ce(IV)-MMD complex in detail. This finding would provide the possibility to systematically control the synthetic parameters and wisely design the precursor components in order to achieve the desired properties of novel materials for specific applications.     

Alternating Metal-Ligand Coordination Improves Electrocatalytic CO2 Reduction by a Mononuclear Ru Catalyst**

Molecular electrocatalysts for CO₂-to-CO conversion often operate at large overpotentials, due to the large barrier for C−O bond cleavage. Illustrated with ruthenium polypyridyl catalysts, we herein propose a mechanistic route that involves one metal center that acts as both Lewis base and Lewis acid at different stages of the catalytic cycle, by density functional theory in corroboration with experimental FTIR. The nucleophilic character of the Ru center manifests itself in the initial attack on CO₂ to form [ Ru -CO₂]⁰, while its electrophilic character allows for the formation of a 5-membered metallacyclic intermediate, [ Ru -CO₂CO₂]^0,c, by addition of a second CO₂ molecule and intramolecular cyclization. The calculated activation barrier for C−O bond cleavage via the metallacycle is decreased by 34.9 kcal mol⁻¹ as compared to the non-cyclic adduct in the two electron reduced state of complex 1 . Such metallacyclic intermediates in electrocatalytic CO₂ reduction offer a new design feature that can be implemented consciously in future catalyst designs.     

Regioselective Photochemical Cycloaddition Reactions of Diolefinic Ligands in Coordination Polymers

The pure diolefinic ligand 1,4‐bis(pyridin‐4‐yl)‐1,3‐butadiene (bpbde) is photostable in the crystalline state. With the assistance of coordination‐driven metal‐organic assemblies, the photoreactivity of this diolefinic ligand can be significantly enhanced. A hydrothermal reaction of bpbde with Cd(NO₃)₂?4 H₂O and the auxiliary ligand adipic acid resulted in the formation of a two‐dimensional photoreactive coordination polymer (CP), [Cd(adipate)(bpbde)]_n ( 1 ). When the aliphatic carboxylic acid was replaced by pimelic acid, another photoreactive CP [Cd(pimelate)(bpbde)]_n ( 2 ) with a three‐dimensional framework was obtained. With irradiation of 365 nm UV light, the bpbde ligands in crystalline 1 and 2 underwent a regioselective photochemical [2+2] cycloaddition reaction and converted to 3,4,7,8‐tetra(pyridin‐4‐yl)tricyclo[4.2.0.0^2,5]octane (tptco) and 1,3‐bis(pyridin‐4‐yl)‐2,4‐bis(2‐(pyridin‐4‐yl)vinyl)cyclobutane (bpbpvcb), respectively. The results provide an interesting insight into the rational design of highly regio‐ or stereoselective photocatalytic reactions for the formation of special organic molecules.     

Homocoupling Reactions of Azoles and Their Applications in Coordination Chemistry

Pyrazole, a member of the structural class of azoles, exhibits molecular properties of interest in pharmaceuticals and materials chemistry, owing to the two adjacent nitrogen atoms in the five-membered ring system. The weakly basic nitrogen atoms of deprotonated pyrazoles have been applied in coordination chemistry, particularly to access coordination polymers and metal-organic frameworks, and homocoupling reactions can in principle provide facile access to bipyrazole ligands. In this context, we summarize recent advances in homocoupling reactions of pyrazoles and other types of azoles (imidazoles, triazoles and tetrazoles) to highlight the utility of homocoupling reactions in synthesizing symmetric bi-heteroaryl systems compared with traditional synthesis. Metal-free reactions and transition-metal catalyzed homocoupling reactions are discussed with reaction mechanisms in detail.     

复杂氧化还原反应配平技巧

复杂氧化还原反应配平技巧,是在突出氧化还原反应本质的前提下,把握多层次的守恒(电子转移守恒,电性守恒—若是离子反应,原子个数守恒),细心观察变化前后的特点,灵活处理反应物中某些元素的价态,突出化学特色,把方程式配平。     

氧化还原反应中2个重要关系式用于求算非氧化还原反应平衡常数的方法讨论

电化学中的KƟ-EƟ关系式和φ-φƟ关系式是分别求算原电池氧化还原反应平衡常数和氧化还原电对电极电势的重要公式。实际上,这2个公式也可以用来求解非氧化还原反应的平衡常数。以实例的形式讨论了这一思想的根据、方法,及其在求算水电离常数、弱酸或弱碱电离常数、难溶性电解质溶度积常数和配离子形成常数等方面的应用。     

氮杂穴状大环钴(Ⅱ)配合物的合成、晶体结构及其催化性能

以一个氮杂穴状大环配体为自由配体,与硝酸钴经配合反应合成了一个新的穴状单核钴配合物[CoL(NO_3)]·(NO_3)·8H_2O(1),其晶体结构经X-射线单晶衍射表征。采用紫外-可见分光光度法对1催化p-硝基苯酚醋酸酯(NA)的水解动力学性质进行了研究。结果表明:催化水解速率对底物(NA)及配合物浓度均呈一级反应,催化水解速率受酸碱平衡影响。