STRUCTURE OF COPPER(II)-BPY AND COPPER(II)-PHEN COMPLEXES - EXAFS AND SPECTROPHOTOMETRIC STUDIES ON THE STRUCTURE OF COPPER(II) COMPLEXES WITH 2,2'-BIPYRIDINE AND 1,10-PHENANTHROLINE IN AQUEOUS-SOLUTION

The structure of copper(II) complexes with 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) in aqueous solution has been studied by EXAFS and spectrophotometric methods. The EXAFS data and electronic spectra for solutions containing [Cu(bpy)]2+, [Cu(bpy)2]2+ and [Cu(bpy)3]2+ complexes as the main species, respectively, showed that the mono(2,2'-bipyridine)copper(II) complex has an axially elongated octahedral structure with four additional water molecules and the tris(2,2'-bipyridine)copper(II) complex also has a distorted octahedral structure. On the other hand, the bis(2,2'-bipyridine)copper(II) complex has a five-coordinate trigonal bipyramidal structure with an additional water molecule. It was also shown that the structure of the mono- and tris(1,10-phenanthroline)copper(II) complexes is axially elongated octahedral similar to the relevant 2,2'-bipyridine complexes. The structure of the bis(1,10-phenanthroline)copper(II) complex was not determinable by the present transmission mode EXAFS experiment because of its very low solubility in water.