Substitution reactions of square-pyramidal [ZnCl2(terpy)] complex (terpy = 2,2′:6′,2″-terpyridine) with biologically relevant nucleophiles such as imidazole, glutathione, 1,2,4-triazole, and pyrazine were investigated at pH 7.0 as a function of nucleophile concentration. The reactions were followed under pseudo first-order conditions by UV-Vis spectrophotometry. The substitution reactions comprised two steps of consecutive displacement of chlorido ligands. Different reaction pathways for the first reaction step of nucleophilic substitution were defined. The order of reactivity of the investigated nucleophiles for the first reaction was imidazole > glutathione > pyrazine > 1,2,4-triazole, while for the second reaction step it was pyrazine > 1,2,4-triazole > imidazole > glutathione.

中文翻译：

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二氯[2,2':6',2"-三联吡啶]锌(II)与生物学相关亲核试剂在水溶液中反应的研究

方锥[ZnCl2(terpy)]复合物（terpy = 2,2':6',2"-terpyridine）与生物相关亲核试剂如咪唑、谷胱甘肽、1,2,4-三唑和吡嗪的取代反应是在 pH 7.0 作为亲核试剂浓度的函数进行研究。通过紫外-可见分光光度法在伪一级条件下跟踪反应。取代反应包括氯配体连续置换的两个步骤。定义了亲核取代的第一个反应步骤的不同反应途径。第一个反应所研究的亲核试剂的反应性顺序是咪唑>谷胱甘肽>吡嗪>1,2,4-三唑，而第二个反应步骤是吡嗪>1,2,4-三唑>咪唑>谷胱甘肽。