团簇Co3NiB2异构化反应的动力学与热力学研究

为确定团簇Co₃NiB₂最终能稳定存在的优化构型并探究不同异构化反应在不同温度下与平衡常数、指前因子之间的关系,基于密度泛函理论与过渡态理论在B3LYP/Lanl2dz水平下结合范特荷夫方程与阿伦尼乌斯方程,分别从化学动力学与化学热力学角度对团簇Co₃NiB₂的异构化反应进行深入讨论.研究结果表明:构型1⁽⁴⁾～4⁽⁴⁾能大量稳定存在,且连串反应7⁽⁴⁾→5⁽⁴⁾→4⁽²⁾→1⁽²⁾最容易发生; 依据范特荷夫方程积分式可知平衡常数的对数ln K与1/T呈线性关系,依据阿伦尼乌斯方程的衍生公式可知ln A与1/T同样呈线性关系; 当T=298.15 K时,ln K与反应物和生成物的能量差ΔE呈正相关关系,且同时满足线性方程ln K(T)=0.404 31ΔE+0.388 26.研究预测团簇各个优化构型所能发生异构化反应的平衡常数K的取值范围为0.946 0～9.431 9×10¹⁹.

The Study on the Dynamics and Thermodynamicsof Isomeric Transformation of Cluster Co3 NiB2

In order to determine the optimized configurations of cluster Co₃NiB₂ and explore the relationship between different isomerization reactions and equilibrium constants,pre-exponential factors at different temperatures,the isomerization of cluster Co₃NiB₂ is thoroughly discussed from the view of chemical dynamics and thermodynamics,based on the density functional theory and transition state theory and combined with Van’t Hoff equation and Arrhenius equation at the B3LYP/Lanl2dz level.The results show that configuration 1⁽⁴⁾—4⁽⁴⁾ can exist in a large amount,and the reaction 7⁽⁴⁾→5⁽⁴⁾→4⁽²⁾→1⁽²⁾ is most easily to occur.According to the integral formula of Van’t Hoff equation,the ln K and 1/T of the equilibrium constant show a linear relationship.According to the derivative formula of Arenius equation,ln A and 1/T also show a linear relationship.When T=298.15 K,the ln K of the equilibrium constant is positively correlated with the energy difference(ΔE)of reactants and products,and meets the linear equation that is ln K(T)=0.404 31ΔE+0.388 26.At the same time,the range of the equilibrium constant K of the isomerization reaction of the optimized configurations is from 0.946 0 to 9.431 9×10¹⁹.