| Research Abstract |
To analyze stereo molecular structures around each metal atom of planar metal complexes in solution which are related to the character of their complexes in solution, we mainly have measured XANES spectra of them, established the spectral analysis method using a DV-Xα molecular orbital calculation method, and clarified the relationship between their structures and chemical characters. The copper (II) complex of (N,N', N", N'''-tetrakis (2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane) forms a dinuclear structure in crystal. If Br^- is a counter anion this complex forms a bridged structure, and forms an unbridged one if ClO_4^- is a counter anion. To discuss the behavior of the complex in solution, we measured XANES spectra of this complex in crystal and in aqueous solution and analyzed the spectra with a DV-Xα method. In case of the Br^- bridged complex, there is no change between both spectra. However, in case of the unbridged complex, the XANES spectra of the complex in aqueous solut
… More
ion show the clear difference with the spectra of the complex in crystal. The DV-Xα calculation for both spectra clarified that the complexes in aqueous solution form a bridged structure by Br^- or oxygen atom (one oxygen atom in ClO_4^- anion). Bis (1,2-dione diozimato) nickel (II) complexes form two different types of one dimensional stacking structures. The crystal samples of the complexes give two different type XANES spectra, however, the pyridine solution samples of them give only the same spectra. We analyzed those spectra by our DV-Xα calculation method using proposed model structures, and clarified the spectral change, between them. In case of solid samples the spectral change at about 8340eV shows the difference between each atomic interaction in their stacking structures, and in case of pyridine solution samples the complexes give the only one structure which the complex molecules are stacked one above the other, although adjacent molecules in the stacking structures slightly deviate from the c axis. The result gives good information for the origin of red color of the complex solution. [CuBr_2(cyclam)] and [Cu(cyclam)(H_2O)_2]F_2-4H_2O are two different type complexes of cyclam, 1,4,8,11-tetraaza cyclotetradencane, and the XANES spectra of these complexes in solid and solution are different with each other. We analyzed the spectra using our DV-Xα method, and the results suggest that the different spectral patterns are caused by exchanging one axial Br^- with an H_2O molecule to Cu(II) in aqueous solution and the predominant complex in aqueous solution is [CuBr(cyclam)(H_2O)]^+. The upper mentioned studies show XANES spectral analysis by our DV-Xα calculation method is very effective method for analyzing stereoscopic inter-atomic interactions in solid and in solution. Less
|
