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~1H NMR不但可以研究分子结构和立体化学,而且在某些适当的金属配合物体系中,还可以研究金属离子和配体间的迁移性及分子内和分子间交换的动态过程。本文用DNMR方法研究了碱土金属Ca和Sr-DTPA配合物的分子内交换过程,取得一些新结果:(1) Ca和Sr-DTPA配合物分子内过程△(?)∧构型转化是个快过程,而N原子反转在NMR时标内属于慢过程;(2) 分子内过程的活化能(E_a)大小主要决定金属离子的半径;(3) 尽管DTPA配体中四个乙酸基参与配位,但由于快速交换平均,可认为配合物是六配位。
~ 1H NMR not only can study molecular structure and stereochemistry, but also in some suitable metal complexes system, we can also study the mobility between metal ions and ligands and the dynamic process of intramolecular and intermolecular exchange. In this paper, the intramolecular exchange process of alkaline earth metal Ca and Sr-DTPA complexes was studied by DNMR and some new results were obtained: (1) △ (¯) ∧ configuration transition of Ca and Sr-DTPA complexes was a fast process (2) the activation energy (E_a) of the intramolecular process mainly determines the radius of the metal ions; (3) although the four acetate groups in the DTPA ligand participate in the coordination , But due to rapid exchange averages, the complex can be considered as a hexacoordination.