L Journal of Alloys and Compounds 300–301 (2000) 360–369 www.elsevier.com / locate / jallcom Synthesis and spectroscopic characteristics of a new class of lanthanide compounds of formulae Ln(HX) (NO ) and Ln(HX) Cl 3 3 3 3 3 a, a b a * ~ Janina Legendziewicz , Grazyna Oczko , Vladimir Amirkhanov , Rafal « Wiglusz , b V.A. Ovchynnikov a Faculty of Chemistry, University of Wrocl «aw, F. Joliot-Curie Str. 14, 50-383 Wrocl «aw, Poland b Institute of Chemistry, Kiev State University, Vladimirskaya 64, 2520033 Kiev, Ukraine Abstract Two series of the lanthanide (Eu, Pr) compounds of the formulae Ln(HX) Cl (1); Ln(HX) (NO ) (2) [where HX5CCl CO–NH– 3 3 3 3 3 3 PO(NEt ) ] with C.N.56 and 9 were obtained in the form of monocrystals. The spectroscopic properties of these compounds were 2 2 investigated at 293, 77 and 4.2 K and the results related to their structures. Correlation was made with the spectroscopic data and structure of the Eu and Nd respective chelates. Essential differences were found in coordination mode of ligand molecules in those systems. Intensity analysis of electronic transitions, electron–phonon coupling, as well as splitting and energies of electronic levels were used as tests of metal bonding in the systems under investigation. The electronic f–f transitions of praseodymium (1, 2) compounds show drastic differences in oscillator strength values, pointing thus at substantial differences in symmetry of the metal centre. Judd–Ofelt parameters were calculated with low errors of estimation. The relatively strong vibronic lines appear at displacement frequencies, corresponding to both ligand and Ln–L localised vibrational modes.  2000 Elsevier Science S.A. All rights reserved. n Keywords: Synthesis; Spectroscopy; Emission; Excitation; Eu(III); Pr(III); Intensity calculations 1. Introduction exhibit biological activities and in vitro tests show their strong anticancer properties [5]. Crystal structure of the Phosphoro-azo derivatives of b-diketones have been second group of complexes explained the kind of b- applied as anticancer agents [1,2]. However, the knowl- diketone bonding mode and formation of complexes with edge about the role of functional groups as well as their C.N.56 and 9 with chloride and nitrate as a counterions. metal complexes in this process is not sufficient yet. The aim of the present studies is to focus on spectro- Recently we investigated the europium and neodymium scopic properties of the compound including electron– complexes with three types of b-diketone derivatives [3– phonon coupling. The main purpose of this report is to 5]. Their structure and spectroscopic properties at 293, 77 show how the structural differences are reflected in the and 4.2 K were reported [3,5]. The normal coordinate general features of the Eu(III) and Pr(III) optical absorp- analysis was done and used in explanation of the IR and tion, excitation and emission spectra. The title compounds Raman data. It was found that depending on pH during are excellent examples to such a analysis. complexation two types of compounds were formed, chelating ML type (I) with strong M–L bond and 4 relatively high covalency determined on the basis of the 2. Experimental nephelauxetic effect that described by Jorgensen [6], and M(HX) L type (II) with the protonated form of ligand Two types, Ln(HX) Cl (1) and Ln(HX) (NO ) (2), 3 3 3 3 3 3 3 molecule [7,8]. The lanthanide chelates of the first group of europium and praseodymium complexes were prepared according to the procedure described in details in [7,8] and were grown up in the form of single crystals of good *Corresponding author. Tel.: 148-71-320-4300; fax: 148-71-328- optical quality and 13233 mm dimensions. 2348. E-mail address: jl@wchuwr.chem.uni.wroc.pl (J. Legendziewicz) Samples were checked by the X-ray methods and 0925-8388 / 00 / $ – see front matter  2000 Elsevier Science S.A. All rights reserved. PII: S0925-8388(99)00766-5