Abstract: Complexes with the general formula Ln(X-P)₃·3H₂O[X=H, 2-Cl, 4-Br, 2CH₃, 3-NO₂, 2-OCH₃, 2,4-dichloro, 3-OH; P=2-(COO)C₆H₄CONHC₆H_5-nX_n, n=1,2; Ln=Pr (Ⅲ), Nd(Ⅱ)] have been synthesized and characterized on the basis of elementry analysis, infrared and reflectance electronic spectra and thermogravimetical methods. The results show that the cpordination occurs by means of two oxygen atoms, one is from the amido and the other from the hydroxyl in the carboxylate. Each complex contains three coordination water molecules. The values of Slater-Condon (F₂, F₄, F₆) interelectronic repulsion and Lande parameter (ξ_4f) spin-orbit interaction parameters have been computed from the spectral data. The average values of F₄/F₂and F₆/F₂have been found to be 0. 137, 0. 0149[Pr (Ⅲ)] and 0.153, 0.0152 [Nd(Ⅲ)], respectively. By using the spectral data, the nephelauxitic ratio (β), average covalency parameters (δ) and average bonding parameters (b^1/2) have been evaluated which indicate weak covalent bonding.

Key words: Rare earth complexes, Infrared spectrometry, Reflectance electronic spectra, Thermogravimetric analysis