高效液相色谱法测定金属配合物{Fe[3-(2-吡啶基)-5，6-二苯基-1，2，4-三嗪]_3}^(2＋)两种几何异构体的动力学转变

Determination of kinetic transformation of two geometrical isomers of the [Fe(PDT)_3]^(2+) by high performance liquid chromatography

通过高效液相色谱法研究了3-(2-吡啶基)-5,6-二苯基-1,2,4-三嗪(PDT)和Fe(Ⅱ)的配合物——[Fe(PDT)3]2+的面式和经式两种几何异构体之间的动力学平衡过程。结果表明:不同温度(30,35,40,45℃)下,两种几何异构体含量(x)之间的相互转变均符合动力学一级反应,其xeln[(xe-x0)/(xe-x)]值和反应时间t(min)之间的关系分别为:xeln[(xe-x0)/(xe-x)]=0.082t+0.729(r2=0.9911,T=45℃),xeln[(xe-x0)/(xe-x)]=0.049t+0.598(r2=0.9987,T=40℃),xeln[(xe-x0)/(xe-x)]=0.022t+0.586(r2=0.9987,T=35℃),xeln[(xe-x0)/(xe-x)]=0.012t+0.591(r2=0.9988,T=30℃)。两种异构体之间的动力学相互转变过程中的活化焓(ΔH)、活化熵(ΔS)和活化能(ΔEa)分别为:ΔH=103.84kJ.mol-1,ΔS=271.93J.mol-1.K-1,ΔEa=86.74kJ.mol-1(面式异构体向经式异构体转变);ΔH=106.47kJ.mol-1,ΔS=257.65J.mol-1.K-1,ΔEa=94.43kJ.mol-1(经式异构体向面式异构体转变)。

The kinetic transformation of the two isomers of the [Fe（PDT）3]2＋（PDT：3-（2-pyridyl）-5,6-diphenyl-1,2,4-triazine）was studied by high performance liquid chromatography.The transformation between two isomers was proved to be treated kinetically as the first-order reaction.At different reaction temperatures,the linear regression equations between xeln[（xe-x0）/（xe-x）] and t（min）were as follows：xeln[（xe-x0）/（xe-x）]=0.082t＋0.729（r2=0.991 1,T=45 ℃）,xeln[（xe-x0）/（xe-x）]=0.049t＋0.598（r2=0.998 7,T=40 ℃）,xeln[（xe-x0）/（xe-x）]=0.022t＋0.586（r2=0.998 7,T=35 ℃）,xeln[（xe-x0）/（xe-x）]=0.012t＋0.591（r2=0.998 8,T=30 ℃）.The activation enthalpy（ΔH）,activation entropy（ΔS）,and activation energy（ΔEa）characterizing the kinetic transformation were as follows：ΔH=103.84 kJ·mol-1,ΔS=271.93 J·mol-1·K-1,ΔEa=86.74 kJ·mol-1（fac-isomer→mer-isomer）;ΔH=106.47 kJ·mol-1,ΔS=257.65 J·mol-1·K-1,ΔEa=94.43 kJ·mol-1（mer-isomer→fac-isomer）.