Uncovering a CF 3 Effect on X‐ray Absorption Energies of [Cu(CF 3 ) 4 ] − and Related Copper Compounds by Using Resonant Diffraction Anomalous Fine Structure (DAFS) Measurements**
Uncovering a CF 3 Effect on X‐ray Absorption Energies of [Cu(CF 3 ) 4 ] − and Related Copper Compounds by Using Resonant Diffraction Anomalous Fine Structure (DAFS) Measurements**
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通过使用共振衍射反常精细结构 (DAFS) 测量揭示 CF 3 对 [Cu(CF 3 ) 4 ] 和相关铜化合物 X 射线吸收能的影响**
DOI：
10.1002/anie.202313744
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Mankad, Neal P.
中科院分区：
文献类型：
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作者：
Alayoglu, Pinar;Chang, Tieyan;Yan, Connly;Chen, Yu‐Sheng;Mankad, Neal P.
了解高价金属配合物的电子结构有助于金属催化交叉偶联方法的进步。[Cu（CF 3）4]−（1）是一个典型的高价配合物，它具有形式上的Cu（III）氧化态，但其物理分析导致一些人在反向配位场模型中将其指定为Cu（I）。最近通过X射线光谱对1进行的检查导致先前的作者得出相互矛盾的结论，从而激发了通过互补方法共振衍射异常精细结构（DAFS）重新检查其X射线吸收曲线。通过对一系列七种单核Cu络合物（包括1）的DAFS测量结果的分析，本文表明，X射线吸收存在系统的三氟甲基效应，使共振Cu K边缘能量蓝移2-3 eV/CF 3，完全解释了观察到的形式Cu（III）络合物（如1）和形式Cu（I）络合物（如（Ph 3 P）3CuCF 3（3））之间DAFS曲线的变化。 因此，与反向配位场模型一致，本文提供的数据意味着，1最好描述为含有Cu（I）离子，dn计数接近10。
Understanding the electronic structures of high‐valent metal complexes aids the advancement of metal‐catalyzed cross coupling methodologies. A prototypical complex with formally high valency is [Cu(CF3)4]−(1), which has a formal Cu(III) oxidation state but whose physical analysis has led some to a Cu(I) assignment in an inverted ligand field model. Recent examinations of1by X‐ray spectroscopies have led previous authors to contradictory conclusions, motivating the re‐examination of its X‐ray absorption profile here by a complementary method, resonant diffraction anomalous fine structure (DAFS). From analysis of DAFS measurements for a series of seven mononuclear Cu complexes including1, here it is shown that there is a systematic trifluoromethyl effect on X‐ray absorption that blue shifts the resonant Cu K‐edge energy by 2–3 eV per CF3, completely accounting for observed changes in DAFS profiles between formally Cu(III) complexes like1and formally Cu(I) complexes like (Ph3P)3CuCF3(3). Thus, in agreement with the inverted ligand field model, the data presented herein imply that1is best described as containing a Cu(I) ion with dncount approaching 10.