双水杨醛缩乙二胺烷基钴(Ⅲ)配合物电化学氧化动力学的研究

用循环伏安法、计时电流法、线性扫描伏安法及lgi～E法研究了双水杨醛缩乙二胺烷基钴(Ⅲ)配合物[RCo(Salen),R=CH₃,C₂H₅,n-C₄H₉,i-C₄H₉]在Au电极上的电化学氧化动力学过程,测定了RCo(Salen)的电极反应的速率常数k_s、电子转移数n₁、电荷传递系数a、标准电极电位E⁰、扩散系数D;同时,还测定了氧化产物化学分解加速率常数k_f及分解产物电解氧化的电子转移数n₂等参数,实验表明RCo(Salen)的电化学反应是ECE过程,R基对E⁰、k_f等均有影响。     

自旋捕集EPR研究三种水合丁基钴肟光解Co-C键断裂产生的自由基的重排反应

以MNP为捕集剂,对三种水合丁基钴肟RCo(DH)₂H₂O(R=n-C₄H₉,#em/em#-C₄H₉,sec-C₄H₉)水溶液进行了光解EPR研究,发现其Co-C键断裂产生的自由基进一步重排的反应.     

辅酶B12模型化合物的研究(Ⅵ)──轴向及平面配体对RCo(salen)L和RCo(SB)L中Co─C键稳定性的影响

合成与表征了两类14种烷基钴Schiff碱配合物RCo(chel)L(R=CH₃,C₂H₅,n-C₃H₇,n-C₄H₉,i-C₄H₉;chel=salen,SB;L=Py,γ-pic,PPh₃),其中RCo(SB)L是一类新的辅酶B₁₂模型化合物,五配位的C₂H₅Co(SB)也是首次报道。研究了在固态和溶液中配合物的性质,并讨论了影响配合物中Co─C键稳定性的因素。     

N,O-配体钴化合物的合成及其环氧丙烷羰化酯化的催化性能

合成了9种N,O-配体化合物L¹～L⁹.化合物L¹～L⁴分别与0.5 equiv.Co₂(CO)₈发生氧化还原配位反应生成中性单核钴化合物1～4;L⁵～L⁷分别与1 equiv.Co₂(CO)₈发生歧化和氧化还原配位反应;L⁸与5/6 equiv.Co₂(CO)₈以及1.2equiv.MeOH和0.4 equiv.H₂O发生歧化和氧化还原配位反应;L⁹与0.5 equiv.Co₂(CO)₈发生歧化配位反应生成同钴核离子对化合物5～9.这些化合物中的阴离子均为[Co(CO)₄]^-.相应地,化合物8中的阳离子是三核钴簇,其它化合物中的阳离子都是单核钴.化合物1～9通过FT-IR谱...     

钴取代型钼硅杂多蓝稀土盐的合成及性质研究

报道了钴取代的钼硅稀土二电子杂多蓝Ln₂H₂[SiMo₁₁Co(H₂O)O₃₉]·nH₂O,(Ln=La,Ce,Pr,Nd,Sm,Gd)的制备和离析方法,并通过元素分析、红外光谱、紫外-可见光谱、循环伏安、热重-差热分析、X射线光电子能谱、电子顺磁共振、²⁹Si核磁共振和磁化率等对产物进行了表征及性质研究.结果表明,杂多蓝的结构与其母体杂多酸相比,结构上发生轻微的畸变,还原过程中,Co²⁺及Ln³⁺均未变化.     

联氨在d-过渡金属配合物MTP(o-NO2)TBP修饰石墨电极上的催化氧化研究

研究了N₂H₄在间-四(邻-硝基苯基)四苯并卟啉铁(Ⅲ)、钴(Ⅱ)、锌(Ⅱ)和镍(Ⅱ)配合物[MTP(o-NO₂)TBP,简称MTBP]修饰石墨电极上的催化电氧化反应,测得该系列金属四苯并卟啉的催化活性的顺序为Co(Ⅱ)TBP>ClFe(Ⅲ)TBP>Ni(Ⅱ)TBP>Zn(Ⅱ)TBP≈石墨,考察了Co(Ⅱ)TBP和ClFe(Ⅲ)TBP催化联氨电氧化反应的动力学过程.结果表明,OH^-和N₂H₄在ClFe(Ⅱ)TBP修饰电极上的反应级数分别为2和1,而在Co(Ⅱ)TBP修饰电极上的均为1.根据电化学参数提出了可能的反应机理.     

光导纤维光谱电化学池的研制及初步应用

研制了光导纤维光谱电化学池(FOSECC),并用该池研究Fe(CN)₆^3-/Fe(CN)₆^4-一氧化还原体系。获得不同电位下的吸收光谱;在不同温度下分别测定了式量电位E°′和反应得失电子数n;求出了体系电极反应的△H°和△S°;计算了FOSECC的灵敏度--摩尔吸收/电位比,结果满意。     

辅酶B_(12)模型化合物的研究 α.RCo(salen) L(R=n-C_3H_7,i-C_4H_9;L=H_2O,py,γ-pic)的电化学性质

用循环伏安法研究了辅酶 B1 2 模型化合物 RCo(salen) L (R=n- C3 H7,i- C4H9;L=H2 O,py,γ-pic)的电化学行为 ,讨论了轴向碱基 L对氧化还原电位的影响。结果表明 :随着碱基 L给电子能力的增强 ,其氧化还原电位均发生负移。     

层状锰酸锂衍生物的阳离子价态与锂电池的电化学性能研究

采用溶胶-凝胶法, 通过锂盐、镍盐、钴盐与锰盐生成锂镍钴锰氧化合物的前驱体, 随后采用高温固相法合成了Li(Mn_1/3Co_1/3Ni_1/3)O₂. 借助于X射线光电子能谱(XPS)、X射线衍射(XRD)、循环伏安(CV)及充放电测试等现代测试手段研究了材料的晶型结构、离子价态及电化学性能. 前驱体经950 ℃煅烧可获得晶体结构完整、晶胞参数为a＝0.2864 nm, c＝1.4235 nm的六方层状Li(Mn_1/3Co_1/3Ni_1/3)O₂化合物; XPS结果表明Li(Mn_1/3Co_1/3Ni_1/3)O₂化合物表面上的Mn, Ni和Co分别以Mn^4＋, Ni^2＋和Co^3＋存在; 材料的高温放电比容量比室温要高, 在55 ℃下, 在2.5～4.6 V电压范围内, 电流密度为28 mA/g时材料首次放电容量195 mAh/g, 循环10次后容量保持在170 mAh/g; 循环伏安曲线上3.7 V和4.4 V的氧化还原过程对应于Ni^2＋/4＋和Co^3＋/4＋氧化还原电对的反应.     

LiCl-KCl熔盐体系中镨(Ⅲ)在镍电极上的电化学行为

采用循环伏安、 方波伏安、 计时电位和开路计时电位等电化学方法研究了Pr(Ⅲ)离子在共晶LiCl-KCl熔盐中Ni电极上的电化学行为及Pr-Ni合金化机理. 结果表明, Pr(Ⅲ)离子的电化学还原过程为三电子转移的一步反应. 与惰性Mo电极上的循环伏安曲线相比, Pr(Ⅲ) 离子在活性Ni电极的循环伏安曲线上还出现了4对氧化还原峰, 表明Pr(Ⅲ)离子在Ni电极上发生欠电位沉积, 是由于生成不同的Pr-Ni金属间化合物. 采用X射线衍射仪和扫描电子显微镜-能谱仪等对恒电位电解的产物进行了表征. 结果表明, 在不同电位下进行恒电位电解时, 每个电位上只得到一种Pr-Ni金属间化合物, 分别为PrNi₂, PrNi₃, Pr₂Ni₇和PrNi₅.     

辅酶B12模型化合物的研究(Ⅷ)──RCo(Salen)L配合物Co-C键氧插入光化学反应产物的表征

辅酶Ｂ_（１２）模型化合物的研究（Ⅷ）──ＲＣｏ（Ｓａｌｅｎ）Ｌ配合物Ｃｏ－Ｃ键氧插入光化学反应产物的表征王志林,易争平,李田,陈瑛,黄志明,杨桂娣,薛德平,陈慧兰（南京大学化学系配位化学国家重点实验室南京,２１００９３）关键词烷基钴Ｓｃｈｉｆｆ碱配?..     

辅酶B_(12)模型化合物的研究(V)RCo(Salen)L配合物Co—C键断裂的动力学

运用光度法研究了RCo(Salen)L配合物在甲醇中热分解反应动力学;测定了Co—C键断裂的速率常数及活化能,得到表观速率常数顺序为i-C3H7>i-C4H9>n-C4H9>n-C3H7>C2H5,活化能顺序为i-C3H7相似文献   

Electrocatalyzed carboxylation of organic halides by a cobalt-salen complex.

The carboxylation of benzylic and allylic chlorides by CO₂ in tetrahydrofuran + hexamethylphosphoramide (40% – 60%) is electrocatalyzed by a cobalt Schiff-base complex Co(Salen). The reactions were performed by controlled-potential electrolysis at the RCo (Salen) reduction potential. The yield of the carboxylic acid formation has been calculated.     

一种新型Eu~(3+)和Zn~(2+)双金属杂核配合物的结构与发光性质

合成了一种新型双金属杂核配合物Eu(TTA)3Zn(Salen).H2O(Salen=双水杨醛缩乙二胺,TTA=2-噻吩甲酰三氟丙酮),并对其进行了结构和荧光性能表征.配合物的晶体属于三斜晶系,Pī空间群.中心Eu(Ⅲ)离子与六个TTA分子的氧原子和Salen分子的两个酚氧原子配位,形成8配位的扭曲四方反棱柱构型.Zn(Ⅱ)离子与Salen分子中的两个酚氧原子和两个氮原子以及一个水分子配位,形成五配位的扭曲的四方锥构型.配合物Eu(TTA)3Zn(Salen).H2O的发光量子效率(18.0%)较配合物Eu(TTA)3.2H2O(12.5%)发光量子效率有明显提高,说明第二配体Zn(Salen).H2O对中心离子有较强的敏化发光作用.     

Co(Ⅲ)(Salen)催化的外消旋环氧化合物不对称开环

用较易得到的(R,R)-1,2-二苯基乙二胺(DPEDA)与-2-羟基-5-甲基-3-叔丁基苯甲醛缩合,得到手性Salen,再与Co络合,氧化后得到Salen型手性催化剂(R,R)-2。(R,R)-2可催化外消旋环氧化物的动力学水解拆分,所得手性二醇和手性环氧化合物对映体过量最高分别可达99%和92%。     

Switchable Polymerization Triggered by Fast and Quantitative Insertion of Carbon Monoxide into Cobalt–Oxygen Bonds

A strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine] from ring-opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co−O bond, allowing for in situ transformation of the ROCOP active species (Salen)Co^III-OR into the OMRP photoinitiator (Salen)Co^III-CO₂R. The proposed mechanism, which involves CO coordination to (Salen)Co^III-OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on-demand sequence control can be achieved for the one-pot synthesis of polyester-b-polyacrylate diblock copolymers (Đ<1.15).     

Switchable Polymerization Triggered by Fast and Quantitative Insertion of Carbon Monoxide into Cobalt–Oxygen Bonds

A strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine] from ring‐opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co?O bond, allowing for in situ transformation of the ROCOP active species (Salen)Co^III‐OR into the OMRP photoinitiator (Salen)Co^III‐CO₂R. The proposed mechanism, which involves CO coordination to (Salen)Co^III‐OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on‐demand sequence control can be achieved for the one‐pot synthesis of polyester‐b‐polyacrylate diblock copolymers (?<1.15).     

Oxygen‐Triggered Switchable Polymerization for the One‐Pot Synthesis of CO2‐Based Block Copolymers from Monomer Mixtures

Switchable polymerization provides the opportunity to regulate polymer sequence and structure in a one‐pot process from mixtures of monomers. Herein we report the use of O₂ as an external stimulus to switch the polymerization mechanism from the radical polymerization of vinyl monomers mediated by (Salen)Co^III?R [Salen=N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine; R=alkyl] to the ring‐opening copolymerization (ROCOP) of CO₂/epoxides. Critical to this process is unprecedented monooxygen insertion into the Co?C bond, as rationalized by DFT calculations, leading to the formation of (Salen)Co^III?O?R as an active species to initiate ROCOP. Diblock poly(vinyl acetate)‐b‐polycarbonate could be obtained by ROCOP of CO₂/epoxides with preactivation of (Salen)Co end‐capped poly(vinyl acetate). Furthermore, a poly(vinyl acetate)‐b‐poly(methyl acrylate)‐b‐polycarbonate triblock copolymer was successfully synthesized by a (Salen)cobalt‐mediated sequential polymerization with an O₂‐triggered switch in a one‐pot process.     

Interaction of aryldiazonium salts with some schiff-base complexes of cobalt and ruthenium

The interaction of aryldiazonium ions with some Schiff-base complexes of cobalt and ruthenium have been studied. With cobalt, one-electron oxidation of [Co(II)Salen] occurred; with [Co(I)Salen] the corresponding Co(III)-aryl complexes were isolated. In the case of ruthenium oxidation also occurs, [Ru(Salen)(CO)py] gave the corresponding monocation. The results, especially for ruthenium, are in contrast to the stabilisation of both nitrosyl and aryldiazonium adducts in analogous porphyrin complexes.