Tuning the valence of the cerium center in (Na)phthalocyaninato and porphyrinato cerium double-deckers by changing the nature of the tetrapyrrole ligands
Tuning the valence of the cerium center in (Na)phthalocyaninato and porphyrinato cerium double-deckers by changing the nature of the tetrapyrrole ligands
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通过改变四吡咯配体的性质来调节(Na)酞菁和卟啉铈双层结构中铈中心的化合价
DOI：
10.1021/ja036017
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发表时间：
2003-10-08
影响因子：
15
通讯作者：
Ng, DKP
中科院分区：
文献类型：
--
作者：
Bian, YZ;Jiang, JZ;Ng, DKP
采用上述方法合成了一系列7种铈与卟啉、酞菁和2，3-萘酞菁等四吡咯配体的双层配合物，并用元素分析和一系列光谱方法进行了表征。通过X-射线衍射分析确定了两个混配[（Na）phthalocyaninato]（porphyrinato）配合物的分子结构，它们具有两个半球形配体，呈现轻微畸变的正方反棱柱几何构型。具有一系列的四吡咯配体具有非常不同的电子性质，这些化合物已被系统地研究了配体的铈中心的价态的影响。基于这些化合物的光谱（UV-vis，near-IR，IR，和拉曼），电化学和结构数据，并与之前报道的其他稀土（III）对应物进行比较，发现铈中心在这些配合物中采用中间价态。由于两个富电子的萘酞菁配体，它在二（四叔丁基萘酞菁）铈中呈现几乎三价的状态，这有利于电子从配体离域到金属中心。对于其余的铈双层，铈中心主要是四价的。化合价（3.59-3.68）已根据其L-III边X射线吸收近边结构（XANES）曲线进行了定量。
A series of 7 cerium double-decker complexes with various tetrapyrrole ligands including porphyrinates, phthalocyaninates, and 2,3-naphthalocyaninates have been prepared by previously described methodologies and characterized with elemental analysis and a range of spectroscopic methods. The molecular structures of two heteroleptic [(na)phthalocyaninato](porphyrinato) complexes have also been determined by X-ray diffraction analysis which exhibit a slightly distorted square antiprismatic geometry with two domed ligands. Having a range of tetrapyrrole ligands with very different electronic properties, these compounds have been systematically investigated for the effects of ligands on the valence of the cerium center. On the basis of the spectroscopic (UV-vis, near-IR, IR, and Raman), electrochemical, and structural data of these compounds and compared with those of the other rare earth(III) counterparts reported earlier, it has been found that the cerium center adopts an intermediate valence in these complexes. It assumes a virtually trivalent state in cerium bis(tetra-tert-butylnaphthalocyaninate) as a result of the two electron rich naphthalocyaninato ligands, which facilitate the delocalization of electron from the ligands to the metal center. For the rest of the cerium double-deckers, the cerium center is predominantly tetravalent. The valences (3.59-3.68) have been quantified according to their L-III-edge X-ray absorption near-edge structure (XANES) profiles.