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A new series of manganese(II), iron(III) and cobalt(III) complexes of 14-membered macrocyclic ligand, (3,6, 10,13,16,19-hexaazabicyclo(6.6.6)icosane-1,8-diamine) have been prepared and characterized by elemental analyses, IR, UV- VIS, 1 H- and 13 C- NMR spectra, magnetic susceptibilities, conductivities, and ESR measurements. Molar conductance mea- surements in DMF solution indicate that the complexes are electrolytes. The ESR spectrum for cobalt(III) complex in CD3OD+10%D2O after exposure to 60 Co-γ-rays at 77 K using a 0.2217 M rad h -1 vicrad source showed g⊥>g||>ge, indicating that, the unpaired electron site is mainly present in the dz2 orbital with covalent bond character. In this case, the ligand hyper- fine tensors are nearly collinear with γ-tensors, so there is no major tendency to bend. Therefore, little extra delocalization via the ring lobe of the dz 2 orbital occurs. However, the ESR spectrum in solid state after exposure to 60 Co-γ-rays at 77 K showed g||>g⊥>ge, indicating that, the unpaired electron site is mainly present in the dx2-y2 ground state as the resulting spec- trum contains a large number of randomly oriented molecules provided that, the principle directions of g and A tensors. Man- ganese (II) complex 2, (H12LMn)Cl4.2H2O, showed six isotropic lines characteristic to an unpaired electron interacting with a nucleus of spin 5/2, however, iron(III) complex 3, (H12LFe)Cl5.H2O, showed spectrum of a high spin 57 Fe (I=1/2), d 5 con- figuration. The geometry of these complexes was supported by elemental analyses, IR, electronic and ESR spectral studies. Complex 1 showed exploitation in reducing the amount of electron adducts formed in DNA during irradiation with low radi |
