THE SYNTHESIS AND DETERMINATION OF THE OCTACOORDINATED STRUCTURE OF PR(III) AND ND(III) COMPLEXES WITH BETA-DIKETONES AND DIOLS IN NON-AQUEOUS SOLUTIONS - EVIDENCE OF SOME PARTICIPATION OF PI-ELECTRON DENSITY OF DIOLS WITH PR(III) AND ND(III) IN COMPLEXATION

The synthesized complexes are of the general structure Ln(beta-diketon ate)(3) diol (where beta-diketonate = benzoyl acetonate (bzac), dibenz oyl methanoate (dbm) and thionyl trifluoroacetonate (ttfa) and (diols) (= butane-1,4- and cis-butene-1,4-diols). The absorption intensity da ta in non aqueous solvents has been analysed in terms of Judd Ofelt in tensity T lambda(lambda = 2, 4, 6) parameters for electric dipole 4f-4 f transitions. beta-diketones are bidentate and function as monofuncti onal ligands coordinating through oxygen donor atoms forming substanti ally stable chelate rings, while diols behave as neutral biodentate li gands coordinating through oxygen. beta-diketone ligands differ only i n the substituents R-1 and R-2 (Fig. 1) while diols differ in the natu re of the bond formed between second and third carbon atoms of the mol ecules. These small chemical and structural differences have been show n to produce significant variation of oscillator strength of certain a bsorption bands. Again, their relative perturbations on 4f-4f transiti on intensities are quite evident in T lambda-parameters estimated for different complexes. Attempts have been made to correlate between the intensity parameter T lambda and oscillator strengths determined from observed spectra of these complexes. The intensity analysis of absorpt ion spectral bands have given sufficient evidence of some sort of inte raction between Pr(III) and Nd(III) with pi-electron density of the do uble bond found in butene-1,4-diol. (C) 1997 Elsevier Science B.V.