Abstract
Complexes of La(III), Nd(III), Pr(III), Sm(III), Tb(III), Dy(III), Ho(III), Er(III) and Yb(III) with hydridotris- and tetrakis(benzimidazol-1-yl)borate anions (L
1
and L
2
) have been prepared and characterized. The spectral parameters β, b
1/2
, δ% and η, evaluated from the electronic spectra of the Pr, Nd, Sm, Ho and Er complexes, suggest the presence of a weak covalent contribution in the metal-ligand bond. The IR spectral data reveal that both L
1
and L
2
behave as tridentate ligands coordinating via the pyridyl and pyrrolic nitrogen atoms of the benzimidazolyl groups.