The investigation of the electronic configurations and charge density of Chromium, Iron and Cobalt transion metal
Date Issued
2004
Date
2004
Author(s)
Wang, Tze-Yuan
DOI
zh-TW
Abstract
The chemical bonds of a complicated molecular system are highly correlated to the electronic configuration and chemical reactions. In order to gain insight on the physical and chemical details of the molecular system, a series of spectroscopic techniques had been used. Synchrotron radiation becomes to be more and more important research facilities these years. In this thesis, the absorption spectra various energy are applied using this facility. Electron deformation density and topological properties are also applied to further our understanding of chemical bond. In the first chapter, the formal oxidation state and the non-innocent behavior of biomimic Iron nitrosyl complexes [PPN][Fe(NO)(S2C6H4)2] are still an open question. X-ray absorption techniques such as iron K’L-edge and Ligand(S’N) K-edge are used. The pre-edge feature are used to characterize the oxidation states of NO, it existed as NO· in the reduced (-2) complex anion, but as NO+ in the (-1) complex anion. The oxidation state of iron is between +1 and +2. The unpaired electron of (-2) complex anion is delocalized between Iron and nitrosyl group however the unpaired electron is delocalized between iron and thiolate ligand in (-1) complex anion. Such delocalization properties are changing with the change in temperature. In the chapter two, complex [Co(bpy)3]2+ is normally a high spin species, when loading these complex into the supercage of zeolite-Y, the thermally driven spin crossover occurred due to the confinement in the supercage of the zeolite-Y framework. A stoichiometric metal-oxalato compound [Co(bpy)3][LiCr(ox)3] is synthesized to confirm the spin crossover phenomenon using the Co K-edge absorption technique. The change in XANES region is mainly due to the difference in the Co-N bond length, little to do with spin state of Co. In the last chapter we demonstrate the chemical bonding with the deformation density and topological analysis of the complex [(C6H6)Cr(CO)3]. Three bond critical points are found between benzene ring and Cr atom and three bond critical points are located between Cr atom and carbonyl ligands. It represents the six-coordinated bonding character. The pre-edge region of Cr K-edge absorption demonstrates the site symmetry of the chromium atom is different from that of di-benzene chromium.
Subjects
吸收光譜
電子組態
電荷密度
仿生錯合物
electronic configuration
absoption specta
biomimic complexes
charge density
Type
thesis
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