配合物生成反应速率常数与平衡常数之间的直线自由能关系——Ⅳ.5位取代-1,10-邻菲啰啉-铜(Ⅱ)与镍(Ⅱ)的金属交换反应动力学和机理研究  

Linear Free Enersy Relationships between Reaction Rate Constants and Equilibrium Constants of Complex Compounds Ⅳ. Kinetic Study of Metal-Exchange Reactions between (5-R-1,10-Phenanthroline) Copper (Ⅱ) and Nickel (Ⅱ)

作　　者：陈荣悌[1] 张启衍 李跃进[1] 

机构地区：[1]南开大学化学系

出　　处：《化学学报》1990年第4期349-354,共6页Acta Chimica Sinica

摘　　要：本文用UV分光光度法研究了Cu(Ⅱ)和5位取代-1,10-邻菲啰啉(5-R-phen)配合物与Ni(Ⅱ)的金属交换反应动力学,实验在25℃、pH2.3—3.5范围内和离子强度为1.0mol·dm_(-3)。条件下进行.结果表明反应对配合物Cu(5-R-phen)^(2+)的浓度呈一级关系,反应通过三条不同的途径进行,这三条途径分别为配合物的离解途径、质子催化离解途径和镍(Ⅱ)亲电缔合途径,反应遵循如下速率方程: r={k_0+k_H[H^+]+k_(Ni)[Ni^(2+)]}[Cu(5-R-phen)^(2+)] 本文根据动力学数据讨论了反应机理,实验结果表明金属交换反应速率随配体碱性减小而增大,配合物Cu(5-R-phen)^(2+)的反应活性和配体5-R-phen的碱性强度之间存在直线自由能关系.The kinetics of the metal-exchange reactions between (5-R-phen) copper (Ⅱ)(R=Me,H,C1,NO_2) and nickel (Ⅱ) has been studied at 25℃ and ioaic strength 1.0mol·dm^(-3) over the pH range 2.3—3.5.The rate of the exchange reactions was measured by a Shimadzu UV-240 spectrophotometer.The reactions appeared to proceed through three different pathways which involved H^+ attack and Ni attack as well as a pH-and nickelindependent dissociation of the complexes.The kinetics conforms to the following rate law. d[Ni(5-R-phen)]/dt=(k_o+k_H[H^+]+k_Ni[Ni^(2+)])[(Cu(5-R-phen)^(2+)] The experimental results indicated that the reaction rate of the three pathways increased with decreasing basicity of the ligand.Some linear free energy relationships were found to exist between the reactivity of Cu (Ⅱ) complexes of 5-R-phen and the base strength of the ligand 5-R-phen.The correlation equations are logk_O=-0.338-0.333pK_2 r=O.986 logk_H=3.29-0.489pK_2 r=0.997 logk_(Nl)=2.47-O.502pK_2 r=0.997 The mechanisms of the reactions were dicussed accordingly.

关 键 词：铜配合物 邻菲罗啉 镍 交换反应 

分 类 号：O614.121[理学—无机化学]