Spectroscopic study of the coordination sphere of Gd(III) in Gd(III)-M(II) complexes with a compartmental ligand, where the local environment around Gd(III) is controlled by (M(II) M(II) = Ni(II), Zn(II) and a vacancy)

摘要

The UV-Vis, IR, NMR and EPR spectra of the Gd(III)-M(II) complexes of N,N'-ethylenebis(3-hydroxysalicylaldimine), H(4)osalen, and their analogues were measured. The obtained spectroscopic data and the results of molecular orbital (MO) calculation suggested the structure of the coordination sphere of the Gd(III) in the complexes. The observed EPR spectra were classified according to the local environment of the Gd(III) ions. These results indicate that the 4f-electrons of the Gd(III) ions are affected by the coordinating ligands and their structures, though the 4f-electrons are shielded by the outer-shell electrons (5s- and 5p-electrons). In other words, one is able to control the structure of the coordination sphere of Gd(III) by substituting an ethylene bridge in propylene and o-phenylene, and by changing M(II) between Ni(II), Zn(II) and a vacancy. The behavior of the 4f-electrons are discussed in connection with the local environments around the Gd(III) ions. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 21]