Reduction of Rare-Earth Metal Complexes Induced by γ Irradiation
Reduction of Rare-Earth Metal Complexes Induced by γ Irradiation
复制标题
γ 辐照引起的稀土金属配合物的还原
DOI：
10.1021/acs.inorgchem.2c02857
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发表时间：
2022
影响因子：
4.6
通讯作者：
Evans, William J.
中科院分区：
文献类型：
--
作者：
Moore, William N.;White, Jessica R.;Wedal, Justin C.;Furche, Filipp;Evans, William J.
研究了γ辐射在冷冻溶液中产生不稳定、低氧化态含稀土金属离子分子物种的实用性。该方法进行了评估，通过照射Ln（III）前体（Ln = Sc，Y，和La）在2-甲基四氢呋喃的固体基质中，在77 K与700 keV的137 Cs源产生的自由电子能够减少的Ln（III）物种。这些实验产生的EPR和UV-可见光谱数据与已知的Ln（II）物质[（C5 H4 SiMe 3）3 YII]1-、[（C5 H4 SiMe 3）3LaII]1-和{ScII[N（SiMe 3）2]3}1-的数据相匹配。用这种方法辐照La（III）配合物LaIII[N（SiMe 3）2] 3，得到与{LaII[N（SiMe 3）2]3}1-一致的EPR和紫外-可见吸收光谱，这种物质以前通过化学还原法制备时难以得到。具体地说，辐照产物表现出被I = 7/2139 La核分裂成八条线的轴向EPR谱（g = 1.98，g|| = 2.06，Aave = 519.1G）。紫外-可见吸收光谱包含中心在390和670 nm处的宽带，其与基于时间依赖性密度泛函理论的三角形配体环境中的La（II）离子一致，所述时间依赖性密度泛函理论定性地再现了所观察到的光谱。另外，通过经由紫外-可见光谱测量随时间的浓度来监测在（C5 H4 SiMe 3）3 YIII的照射期间[（C5 H4 SiMe 3）3 YII]1-物质的形成速率，以提供关于玻璃中分子物质经由γ照射还原的速率的数据。
The utility of γ irradiation for generating unstable, low oxidation state molecular species containing rare-earth metal ions in frozen solution has been examined. The method was evaluated by irradiating Ln(III) precursors (Ln = Sc, Y, and La) in a solid matrix of 2-methyltetrahydrofuran at 77 K with a 700 keV137Cs source to generate free electrons capable of reducing the Ln(III) species. These experiments yielded EPR and UV–visible spectroscopic data that matched those of the known Ln(II) species [(C5H4SiMe3)3YII]1–, [(C5H4SiMe3)3LaII]1–, and {ScII[N(SiMe3)2]3}1–. Irradiation of the La(III) complex LaIII[N(SiMe3)2]3by this method gave EPR and UV–visible absorption spectra consistent with {LaII[N(SiMe3)2]3}1–, a species that had previously eluded preparation by chemical reduction. Specifically, the irradiation product exhibited an axial EPR spectrum split into eight lines by theI= 7/2139La nucleus (g⊥= 1.98,g||= 2.06,Aave= 519.1 G). The UV–visible absorption spectrum contains broad bands centered at 390 and 670 nm that are consistent with a La(II) ion in a trigonal ligand environment based on time-dependent density functional theory which qualitatively reproduces the observed spectrum. Additionally, the rate of formation of the [(C5H4SiMe3)3YII]1–species during the irradiation of (C5H4SiMe3)3YIIIwas monitored by measuring the concentration via UV–visible spectroscopy over time to provide data on the rate at which a molecular species is reduced in a glass via γ irradiation.