SPECIFIC FEATURES OF ABSORPTION-SPECTRA OF NEPTUNIUM(IV) COMPLEXES WITH UNSATURATED HETEROPOLY COMPOUNDS

The electronic absorption spectra measured for a number of crystalline compounds and their aqueous solutions show that on going from solutio n to solid compound the coordination sphere of Np(IV) in complexes wit h unsaturated heteropolyanions (HPAs) does not change significantly. C hanges in the nature of the heteropolyanion leaves the general appeara nce of the spectra unaffected, while the f-d-transition bands shift to the short-wave region as the central atom of the heteropolyanion grow s in size. On going from complexes of Np(IV) with HPA to decatungstate relative intensities of the absorption bands notably change.