STRUCTURAL STUDIES ON NEW CO POLYAMINE COMPLEXES BY X-RAY-ABSORPTION FINE-STRUCTURE SPECTROSCOPY

X-ray absorption fine structure (XAFS) studies are performed for a new Co(II) polyamine complex, N,N'-bis(3-aminopropyl)-1,3-propanediamine Co(II) complex (Co-APPD), and related complexes. The observed Co K-edg e XANES spectra show that Co-APPD complex reacted with oxygen (Co-APPD (O-2)) has a trivalent cobalt atom and has the octahedral structure ar ound Co, whereas the difference in the structure between solid Co-APPD and Co-APPD dimethylsulfoxide (DMSO) solution is small. We also find the distortion from octahedral to tetrahedral structure with the incre ase of 2-furancarboxylic acid (FRA) concentration in DMSO solution. Wi th the aid of short-range-order multiple scattering calculation, we st udy the Co K-edge X-ray absorption near edge structure (XANES) spectra of Co-APPD and Co-APPD (O-2) in more detail. From this theoretical st udy, we obtain information about oxygen bonding angle: the bond angle Co-O-O is about 120 degrees.