Dicerium letterbox-shaped tetraphenolates: f-block complexes designed for two-electron chemistry
Dicerium letterbox-shaped tetraphenolates: f-block complexes designed for two-electron chemistry
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DOI：
10.1039/c9dt03291f
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发表时间：
2020-01-21
影响因子：
4
通讯作者：
Slawin, Alexandra M. Z.
中科院分区：
文献类型：
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作者：
Arnold, Polly L.;Wang, Kai;Slawin, Alexandra M. Z.
通过使用四酚盐pTP作为支持的螯合O-供体配体平台，可获得具有稳健Ln-配位的分子双核Ce-III和Pr-III络合物的罕见实例，pTP = [{2-（OC 6 H2 R2 - 2，4）（2）CH}-C6 H4 - 1，4]（4-），其有利于稀土可获得的更高形式氧化态。两类配合物已从平台;一个金属杂环2 + 2 [Ln（2）（pTP）（2）]框架与刚性，信箱形的几何形状和[Ln（芳基氧化物）（4）]核心，和一个更灵活的[（LnX）（2）（pTP）]与一个稀土离子在平台的两端。Ln（III）信箱络合物具有两个K+抗衡阳离子，其中一个位于信箱内，充分强烈地结合平台的两个中心芳烃，使得其不能被溶剂分子（THF和吡啶）或冠醚置换。Ce-III信箱的氧化很容易，并形成不寻常的中性分子（Ce-IV）（2）信箱，其中Ce-IV还原电位为-1.83V vs. Fc/Fc（+）。Ce（III/IV）配合物的电子结构使用HERFD-XAS（高能量分辨率荧光检测X射线吸收光谱）进行了研究。
Rare examples of molecular, dinuclear Ce-III and Pr-III complexes with robust Ln-coordination are accessible by use of the tetraphenolate pTP as a supporting, chelating O-donor ligand platform, pTP = [{2-(OC6H2R2-2,4)(2)CH}-C6H4-1,4](4-) that favours the higher formal oxidation states accessible to rare earths. Two classes of complexes have been made from the platforms; one metallacyclic 2 + 2 [Ln(2)(pTP)(2)] framework with a rigid, letterbox-shaped geometry and [Ln(aryloxide)(4)] core, and one more flexible [(LnX)(2)(pTP)] with one rare earth ion at either end of the platform. The Ln(III) letterbox complexes have two K+ counter-cations, one of which sits inside the letterbox, binding the two central arenes of the platform sufficiently strongly that it cannot be displaced by solvent molecules (THF and pyridine) or crown ethers. Oxidation of the Ce-III lettterboxes is facile and forms the unusual neutral molecular (Ce-IV)(2) letterbox in which the Ce-IV reduction potential is -1.83 V vs. Fc/Fc(+). The electronic structure of the Ce(III/IV) complexes was investigated using HERFD-XAS (high energy resolution fluorescence detection X-ray absorption spectroscopy).