Synthesis and characterization of complexes of early actinides with tridentate schiff base ligands

Abstract

A series of thorium(IV) and dioxouranium(VI) complexes have been synthesised with tridentate schiff base ligands (N₂O donor set) obtained by <i>in situ </i> condensation of N, N-dimethylethylenediamine with <i>o</i>-hydroxy aromatic aldehydes such as salicylaldehyde (HL) or <i>o</i>-hydroxy naphthaldehyde (HL´). While with dioxouranium(VI), the ligands are coordinated in a neutral manner and act as tridentate donors forming complexes of the type UO₂(HL)X₂ or UO₂(HL´)X₂ (X = Cl, I, NCS, NO₃, CH₃COO) with thorium(IV) they are coordinated as deprotonated tridentate ligands yielding complexes of the type Th(L´)₂X₂ (X = I, NCS, NO₃). The IR spectra show that the thiocyanate group is actually N-bonded unidentate isothiocyanate and both the nitrate and the acetate groups are bonded in bidentate manner while the ligands are bonded in tridentate manner in these complexes. The PMR spectra confirm the mode of bonding of the ligands either as neutral or as deprotonated species. The thermogravimetric analyses indicate the stability of the complexes.