Aspects of actinide-Schiff base chemistry
Complexes of tetravalent uranium and thorium have been prepared with the tetradentate ligands N, N’-ethylenebis(salicylaldimine), N,N’-o-phenylenebis(sali-cylaldimine) and the analogous ligands containing substituent groups in the salicylaldimine benzene rings (i.e. 3-MeO, 3-EtO, 5-Cl, 5-NO2). Attempts to form bidentate salicylaldimine complexes were impeded by hydrolysis and oxidation; however, the metal complexes with N-Mesalicylaldimine, N-Etsalicylaldimine and N-phenylsalicylaldimine have been isolated. X-ray powder patterns for these complexes are reported. X-ray structural studies have revealed the salicylaldehyde, N-Mesalicylaldimine, N-Etsalicylaldimine and N,N’-o-phenylenebis(salicylaldimine) complexes of thorium to be eight co-ordinate, with the salicylaldimine complexes having distorted square antiprismatic co-ordination and the salicylaldehyde complex displaying a dodecahedral configuration. U.V., visible and near-I.R. spectra of Schiff-base complexes of thorium, uranium, thallium and lithium are also reported and discussed.