In this project the synthesis and characterization of the complexes with possible bio- and electro- or photochemical applications have been discussed Co{(pyrol)2dien}(Amine)]B(Ph)4 Amine: py, 4-Mepy, 4-Acpy ] [CoIII{(thiophen)2dien})N3)3] [CoIII{(thiophen)dien}2](ClO4)3 Co{(pyrol)2dien}(N3)2 The complexes, ( 1 ) to ( 6 ) are synthesized in good yield and are characterized by FT-IR, UV-Vis and 1 H-NMR spectroscopy and elemental analyses. The structure of complex ( 3 ) have been determined by X-ray crystallography, and the correlation between structural and spectroscopic properties are discussed. It seems that for cobalt , Die is tetradentate and DieNN is pentadentate ligand.. The steric effects on the structural properties of these complexes are discussed and compared with those of similar complexes that have been reported. The electrochemical properties of complexes ( 2 ), ( 3 ), ( 4 ), ( 5 ) and ( 6 ) are also studied by cyclic voltammetery. The results show that the reduction of Co(III) to Co(II) is irreversible and there is direct correlation between the redox potentials and the pK b of axial amines .
