SYNTHESIS AND CHARACTERIZATION OF COMPLEXES OF EARLY ACTINIDES WITH TRIDENTATE SCHIFF-BASE LIGANDS

A series of thorium(IV) and dioxouranium(VI) complexes have been synth esised with tridentate schiff base ligands (N2O donor set) obtained by in situ condensation of N, N-dimethylethylenediamine with o-hydroxy a romatic aldehydes such as salicylaldehyde (HL) or o-hydroxy naphthalde hyde (HL'). While with dioxouranium(VI), the ligands are coordinated i n a neutral manner and act as tridentate donors forming complexes of t he type UO2(I-IL)X(2) or UO2(HL')X(2) (X = Cl, I, NCS, NO3, CH3COO) wi th thorium(IV) they are coordinated as deprotonated tridentate ligands yielding complexes of the type Th(L')(2)X(2) (X = I, NCS, NO3). The I R spectra show that the thiocyanate group is actually N-bonded unident ate isothiocyanate and both the nitrate and the acetate groups are bon ded in bidentate manner while the ligands are bonded in tridentate man ner in these complexes. The PMR spectra confirm the mode of bonding of the ligands either as neutral or as deprotonated species. The thermog ravimetric analyses indicate the stability of the complexes.