Electronic Configuration and Ligand Nature of Five-Coordinate Iron Porphyrin Carbene Complexes: An Experimental Study
Electronic Configuration and Ligand Nature of Five-Coordinate Iron Porphyrin Carbene Complexes: An Experimental Study
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五配位铁卟啉卡宾配合物的电子构型和配体性质：实验研究
DOI：
10.1021/jacs.7b01722
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发表时间：
2017-04-12
影响因子：
15
通讯作者：
Li, Jianfeng
中科院分区：
文献类型：
--
作者：
Liu, Yulong;Xu, Wei;Li, Jianfeng
利用两种卡宾配体(CCL2和CPh2)，用单晶X-射线、X-射线近边吸收光谱、穆斯堡尔谱、核磁共振和紫外可见光谱研究了五配位铁卟啉卡宾配合物[Fe(TPP)(CCL2)](TPP=四(五氟苯基)卟啉)、[Fe(TTP)(CCL2)](TTP=四苯基卟啉)、[Fe(TTP)(CCL2)]和[Fe(TTP)(CCL2)]。X-射线光电子能谱(XANES)表明了配合物的铁(II)氧化状态。多温度和强磁场穆斯堡尔实验显示了很大的四极分裂(QS，E-Q)，确定了S=0的电子组态。更重要的是，结合结构和穆斯堡尔谱研究，特别是与具有强双原子配体(CS，CO和CN-)的低自旋铁(II)卟啉配合物的比较，揭示了卡宾配体的共价键性质。首次建立了这些给体碳配体(：C-R)的铁异构体位移(IS，增量)与轴向键距之间的关系。
The five-coordinate iron porphyrin carbene complexes [Fe(TPP) (CCl2)] (TPP = tetraphenylporphyrin), [Fe(TTP) (CCl2)] (TTP = tetratolylporphyrin) and [Fe(TFPP) (CPh2)] (TFPP = tetra(pentafluoro-phenyl)porphyrin), utilizing two types of carbene ligands (CCl2 and CPh2), have been investigated by single crystal X-ray, XANES (X-ray absorption near edge spectroscopy), Mossbauer, NMR and UV-vis spectroscopies. The XANES suggested the iron(II) oxidation state of the complexes. The multitemperature and high magnetic field Mossbauer experiments, which show very large quadrupole splittings (QS, Delta E-Q), determined the S = 0 electronic configuration. More importantly, combined structural and Mossbauer studies, especially the comparison with the low spin iron(II) porphyrin complexes with strong diatomic ligands (CS, CO and CN-) revealed the covalent bond nature of the carbene ligands. A correlation between the iron isomer shifts (IS, delta) and the axial bond distances is established for the first time for these donor carbon ligands (:C-R).