镧与二溴一氯偶氮胂配位反应动力学及机理研究

STUDIES ON KINETICS AND MECHANISM OF COORDINATION REACTION BETWEEN LANTHANIUM AND DIBROMOCHLOROARSENAZO

本文提纯了二澳一氯偶氮肿(DBCA),纯度达97%以上。测定了镧与DBCA(以H_6R表示,下同)的配应比为La^(3+)(H_2O)_6:H_6R=1:3。用停流分光光度法研究了镧与DBCA配位反应的动力学。获得经验速率方程为R=k[La^(3+)(H_2O)_6][H_6R]~2[H_3^+O]^(-1),实验活化能为54.26KJ·mol^(-1),活化焓为51.82KJ·mol^(-1),活化熵为-86.55J·K^(-1)。拟定了反应机理,由此机理导出的速率方程与经验速率方程相吻合。最后讨论了配合物的几何构型和反应模式。

Dibromochloroarsenazo (DBCA) was purified to an extent of above 97%. The coordinate ratio of lanthanium and DBCA was measured as La^(3+)(H_2O)_6: H_6R=1:3. The kinetics of coordination reaction Was studied by using stop flow spectrophotometry. The rate law is R=k[La^3 (H_2O)_6][H_6R]~2[H_3^+O]^(-1). The Arrhenius activation energy is 54.26KJ·mol^(-1), The activation enthalpy is 51.82 KJ·mol^(-1). And the activation entropy is -86.55J·K^(-1). Referring to Eigen—Tamm mechanism and reference[5], the reaction mechanism was determined and the rate equation was found to be consistent with rate law. It shows that the assumed reaction mechanism is reasonable. In the end the geometrical configuation of activatd complex and reaction mode are discussed.