Some lanthanide complexes of N-(2-pyridyl) acetamide

The complexes formed in the reaction between some lanthanide perchlorates and N-(2-pyridyl)acetamide (aapH) have been prepared and characterized. The compounds have the formulae [Ln(aapH)₄] (ClO₄)₃ (where Ln  Pr, Nd, Eu, Gd, Ho, Yb and Lu) and are solid crystalline substances. The new compounds were characterized by means of chemical analyses, molar conductivities, vibrational spectra, thermograviemetry and electronic absorption and emission spectra. The vibrational spectra and molar conductances indicate that the perchlorate groups are ionic and that aapH acts as a bidentate ligand through the carbonyl oxygen and the ring nitrogen. The PMR of La(aapH)₄ (ClO₄)₃ and [Lu(aapH)₄]ClO₄)₃ reveals that the ligands are planar and corroborates the vibrational evidence that they coordinate in a bidentate manner. The oscillator strength (P_exp) of the hypersensitive transition of the Nd(III) complex has been studied and the nephelauxetic effect has been evalauted. The emission of the Eu(III) complex at 77° is very intense and a tentative assignment of its symmetry has been made.