Revisiting the electronic ground state of copper corroles
Revisiting the electronic ground state of copper corroles
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DOI：
10.1002/anie.200603676
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Holthausen, Max C.
中科院分区：
文献类型：
--
作者：
Broering, Martin;Bregier, Frederique;Holthausen, Max C.
络合物中金属中心的氧化态是目前争论的热点。[1-4]据报道，高价金属离子存在于铜、铁、铬、钴和锰原料中。推测这些配合物中的辅助配体具有非无辜的特征，刺激了这一领域的新兴趣。金属卟啉通常被用作讨论金属配体的参考化合物，尽管金属配体和卟啉配体的N4空腔的大小以及金属-配体相互作用的强度存在显著差异。一个较好的参考配体是具有收缩N4核的corrole和卟啉双负电荷的芳香类卟啉。我们现在已经确定了10-甲咯作为理想的参考体系。在此，我们提出了一个比较研究的同结构铜配合物与10-氧氯和氯氯配体，其中金属离子具有不同的形式，但相同的物理氧化态。铜螯合物是具有抗磁性基态的简单类卟啉金属配合物。根据x射线衍射（XRD， CuÀN短距离）、紫外/可见（类卟啉光谱型）和1HNMR（低温下芳香信号的低场位移）光谱分析，这些配合物中的中心铜离子被指定为+ 3，[1]的氧化态。这些发现随后被一些相关的铜元素的作者所证实DFT计算、电化学研究和拉曼光谱为铜螯合物作为具有低空三重态激发态的典型低自旋铜-(III)配合物的解释提供了额外的支持在我们对开链四吡咯2,2 ' -联二吡啶氧化大环化的研究中，我们观察到，在无水硫酸铜（II）处理下，1是
The oxidation state of the metal centers in corrole complexes is currently a topic of lively debate.[1–4] High-valent metal ions have been reported to be present in copper, iron, chromium, cobalt, and manganese corroles. Speculation that the corrole ligand in these complexes has a non-innocent character has stimulated renewed interest in this field. Metal porphyrins are usually employed as reference compounds for the discussion of metal corroles, despite the fact that the sizes of the N4 cavities of corrole and porphyrin ligands—and, thus, the strength of the metal–ligand interactions—differ significantly. A better reference ligand would be an aromatic porphyrinoid with the contracted N4 core of corrole and the double negative charge of porphyrin. We have now identified 10-oxacorrole as an ideally suited reference system. Herein, we present a comparative study of isostructural copper complexes with 10-oxacorrole and corrole ligands, in which the metal ions have different formal, yet identical physical oxidation states.[5]Copper corroles are simple porphyrinoid metal complexes with a diamagnetic ground state. The central copper ion in these complexes has been assigned an oxidation state of+ 3,[1] on the basis of X-ray diffraction (XRD; short CuÀN distances), and UV/Vis (porphyrinoid spectral type) and 1HNMR (low-field shift of the aromatic signals at low temperature) spectroscopy. These findings were subsequently confirmed by several authors for a number of related copper corroles.[2] DFT calculations, electrochemical studies, and Raman spectroscopy have provided additional support for the interpretation of copper corroles as typical low-spin copper-(III) complexes with a low-lying triplet excited state.[3] During our studies on the oxidative macrocyclization of open-chain tetrapyrrolic 2, 2’-bidipyrrins, we observed that, upon treatment with anhydrous copper (II) sulfate, 1 is