Abstract—

The title complex is formed in a quantitative yield in diluted solutions and the kinetics of its template synthesis and its acidic decomposition were photometricaly studied. The effective synthesis rate constants were determined as the pseudo-first-order rate constants with respect to the concentration of Fe²⁺ ions. The orders with respect to those of nioxime, CH₃B(OH)₂ and H⁺ ions are equal to 3, 1 and –1, respectively. The plausible pathway of its assembly includes a reversible formation of the protonated pseudooctahedral iron(II) tris-nioximate, followed by its monodeprotonation and addition of CH₃B(OH)₂. Thus obtained pseudooctahedral intermediate undergoes a rate-determining stage of double cyclization with elimination of two molecules of water and structural rearrangement as well, thus giving the trigonal-prismatic iron(II) semiclathrochelate monocation. The latter complex easily undergoes a cross-linking with CH₃B(OH)₂, resulted in elimination of H⁺ ion and in formation of the title clathrochelate. Its acidic decomposition rate constants were also obtained as the pseudo-first-order rate constants, but with respect to the concentration of this complex. This rate substantially increases with increase in activity of H⁺ ions and decreases in the presence of CH₃B(OH)₂.

中文翻译：

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甲基硼酸交联形成的笼形螯合物铁（II）三环己烷二酮-1,2-二氧肟酸酯（Nioximate）的模板合成和酸性分解的动力学和热力学

摘要-

在稀释溶液中以定量产率形成标题配合物，并对其光度法研究了其模板合成和酸性分解的动力学。将有效合成速率常数确定为相对于Fe ²⁺离子浓度的拟一级反应速率常数。关于尼肟，CH ₃ B（OH）₂和H ⁺离子的顺序分别等于3、1和–1。其组装的可能途径包括可逆地形成质子化的伪八面体三氧肟酸铁（II），然后进行单去质子化并添加CH ₃ B（OH）_2。。如此获得的拟八面体中间体经历了双环化的速率确定阶段，其中消除了两个水分子并进行了结构重排，从而得到了三角棱晶型铁（II）半铁螯合物单阳离子。后者的络合物​​容易与CH ₃ B（OH）₂发生交联，从而消除H ⁺离子并形成标题笼形螯合物。还获得了其酸性分解速率常数作为拟一级反应速率常数，但相对于该配合物的浓度而言。该速率随着H ⁺离子活性的增加而显着增加，而在CH ₃ B（OH）₂的存在下降低。