Abstract
Some complexes of cerium(IV), thorium(IV), and uranium(IV) and trivalent lanthanide ions with the anions of quadridentate Schiff bases, e.g., NN'-ethylenebis(5-t-butylsalicylideneimine) have been prepared, and their properties investigated by chemical analysis, molecular weight and conductivity measurements, infra-red, visible, and ultra-violet absorption spectroscopy, nuclear magnetic resonance spectroscopy, and X-ray powder diffraction studies. It has been shown from molecular weight and conductivity measurements, and nuclear magnetic resonance spectroscopy that the complexes of tetra-valent metal ions are monomeric and unionized in solution, and the complexes of trivalent metal ions are largely polymeric in solutions of non-polar solvents. The similarity of the visible absorption spectra in the solid and solution phases suggests the solids have the same structures the solution species. The coordination number of Nd2(t-Busalen)3 has been deduced through the hypersensitive transitions observed in the visible region of the absorption spectrum by comparison with the spectra of complexes of Known structure. The same values were found for both in solid complexes and in solution. By X-ray powder photography isomorphism was found in some cases. Complexes of iron(II) with the anions of the quadridentate Schiff bases, NN'-ethylenebis (salicylideneimine) and NN'-phenylenebis(salicylideneimine) have been prepared and shown from magnetic and Mossbauer investigations to contain high-spin iron(II)., These ligands take up planar configurations around bivalent metals but the complexes are believed to have six-coordinate structures. Complexes with potentially pentadentate ligands have also been prepared and may have five-coordinate structures. By reaction with nitric oxide, the iron complexes apparently form penta-coordinate mononitrosyls in the case of quadridentate ligands and hexa-coordinate mononitrosyls in the case of pentadentate ligands. The mononitrosyl compounds are high-spin, with room temperature moments corresponding to three unpaired electrons. A complex of cobalt(II) with the anion of NN'-ethylenebis(5-t-butyl-salicylaldimine) and its nitric oxide complex, a complex of iron(II) with the anion of the bidentate Schiff base ligand, 5-t-butylsalicyl-aldimine, and the pyridine adduct formed by bis(5-t-butylsalicylalde-hydato)iron(II) have also been investigated.