| Popis: |
The work is focused on preparation and characterization of octahedral Fe(II) complexes of 2,2′:6′,2′′-terpyridine (tpy) substituted in 4' position by various groups: Cl (tpyCl), chlorophenyl (tpyPhCl) and 2-thienyl (Ttpy)). Formation and stability of prepared complexes were studied by UV/vis spectroscopy on the basis of titration of tpy ligands by Fe(II) ions. The molar absorption coefficient of the metal-to-ligand charge transfer (MLCT) band was found to increase in the order: tpy < tpyCl < tpyPhCl < Ttpy. The MLCT band position increases in the same order, starting from 551 nm for [Fe(tpy)2]2+ to 576 nm for [Fe(Ttpy)2]2+ . Raman scattering (RS) spectra of tpy ligands were obtained upon non-resonance 780 nm excitation. Four excitation wavelengths (445, 532, 633 a 780 nm) were used for measurement Fe(II) complexes. The excitation profiles of both Raman scattering and surface-enhanced Raman scattering (SERS) spectra were constructed for [Fe(tpyCl)2]2+ complex. On the basis of DFT calculations performed for this complex, the Raman active modes have been assigned to the symmetry species of the D2d point group. Similarly as for the previously studied [Fe(tpy)2]2+ complex, activation of E modes in the region of MLCT band suggests contribution of Herzberg-Teller mechanism to the overall molecular... |
