To optimize the factors affecting the generation and stability of [M(L)][Cp′₃Y^II] complexes (Cp′ = C₅H₄SiMe₃), reductions of Cp′₃Y^III with nine different combinations of alkali metals (M = Li, Na, K, Rb, Cs) and chelating agents (L = 2.2.2-cryptand, 18-crown-6, and dibenzo-18-crown-6) have been examined. The thermal decomposition of each [M(L)][Cp′₃Y^II] product in THF at room temperature was monitored via UV–vis spectra collected over time, and the decomposition profiles were compared. The most stable M/L combination was found to be [K(crypt)][Cp′₃Y^II] with a decomposition t_1/2 ≈ 71 ± 7 min at an 80 mM concentration. The reduction reaction that generates [K(18-crown-6)][Cp′₃Y^II] can be cleanly reversed by addition of Hg to generate the starting materials, Cp′₃Y^III and 18-crown-6, and potassium mercury amalgam.

中文翻译：

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优化碱金属 (M) 和螯合物 (L) 组合以实现 [M(L)][(C5H4SiMe3)3Y] 钇 (II) 配合物的合成和稳定性

为了优化影响 [M(L)][Cp' ₃ Y ^II ] 配合物 (Cp' = C ₅ H ₄ SiMe ₃ )生成和稳定性的因素，用九种不同的碱金属组合还原 Cp' ₃ Y ^III (M = Li、Na、K、Rb、Cs) 和螯合剂 (L = 2.2.2-cryptand、18-crown-6 和 dibenzo-18-crown-6) 已被检查。通过随时间收集的紫外-可见光谱监测室温下每种 [M(L)][Cp' ₃ Y ^II ] 产物在 THF 中的热分解，并比较分解曲线。发现最稳定的 M/L 组合是 [K(crypt)][Cp' ₃ Y ^II]在 80 mM 浓度下分解t _1/2 ≈ 71 ± 7 分钟。生成 [K(18-crown-6)][Cp' ₃ Y ^II ]的还原反应可以通过添加 Hg 完全逆转以生成起始材料 Cp' ₃ Y ^III和 18-crown-6 以及钾汞合金。