Chiral Tectonics: VCD and ECD Application for Epimerization of a Star-Burst Tetranuclear Complex with a Labile Central Core
Chiral Tectonics: VCD and ECD Application for Epimerization of a Star-Burst Tetranuclear Complex with a Labile Central Core
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DOI：
10.3390/inorganics6030070
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发表时间：
2018-07
期刊：
影响因子：
2.9
通讯作者：
Hisako Sato;Fumio Sato;A. Yamagishi
中科院分区：
文献类型：
--
作者：
Hisako Sato;Fumio Sato;A. Yamagishi
本文报道了应用振动圆二色性（VCD）和温度依赖性电子圆二色性（ECD）方法来揭示溶液中具有不稳定中心核的星爆四核金属络合物的动力学方面。单手手性惰性构造 Δ- 或 Λ-[Ru(III)(acac)2(taetH)]（acacH = 乙酰丙酮，taetH2 = 四乙酰乙烷）是通过 [Ru(acac)3] 与 taetH2 在固体中在 120 °C 下反应制备的。通过色谱法获得纯对映体的ΔΛ对。将 Al(ClO4)3 添加到其对映体纯溶液中后，三个单手构造单元在铝 (III) 离子周围自发组装，形成星爆四核络合物 [{Δ- 或 Λ-Ru(acac)2(taet)}3Al(III)]。配合物CDCl3溶液记录的VCD光谱表明，在低于-10°C的温度下，Al(III)离子周围的中心手性主要采取与外围Ru(III)单元相反的绝对构型。该复合物在溶液中围绕中心 Al(III) 核（或差向异构化）进行 Δ 和 Λ 构型之间的相互转化。活化能垒由 CHCl3 和 CH3OH 中 ECD 光谱的时间过程确定。
The present article reports the application of vibrational circular dichroism (VCD) and temperature-dependent electronic circular dichroism (ECD) methods to reveal the dynamical aspects of a star-burst tetranuclear metal complex with a labile central core in a solution. One-handed chiral inert tecton, ∆- or Λ-[Ru(III)(acac)2(taetH)] (acacH = acetylacetone, taetH2 = tetraacetylethane), was prepared by reacting [Ru(acac)3] with taetH2 in solid at 120 °C. The ∆Λ-pair of pure enantiomers was obtained chromatographically. On adding Al(ClO4)3 to its enantiopure solution, three units of one-handed tecton were assembled spontaneously around an aluminum(III) ion to form a star-burst tetranuclear complex, [{∆- or Λ-Ru(acac)2(taet)}3Al(III)]. The VCD spectrum recorded on the CDCl3 solution of the complex showed that the central chirality around an Al(III) ion took dominantly the absolute configuration antipodal to those of peripheral Ru(III) units at the temperature lower than −10 °C. The complex underwent interconversion between the ∆- and Λ-configurations around a central Al(III) core (or epimerization) in solution. The activation energy barrier was determined from the time courses of ECD spectra in CHCl3 and CH3OH.