Electron transfer and 5f→6f transitions in uranium(IV), neptunium(IV), plutonium(IV) hexahalides
Titel:
Electron transfer and 5f→6f transitions in uranium(IV), neptunium(IV), plutonium(IV) hexahalides
Auteur:
Ryan, J. L. Jørgensen, Chr. Klixbull
Verschenen in:
Molecular physics
Paginering:
Jaargang 7 (1964) nr. 1 pagina's 17-29
Jaar:
1964
Inhoud:
Absorption spectra of solutions in acetonitrile of tetra (ethyl) ammonium salts of UCl6--, UBr6--, UI6--, NpCl6--, NpBr6--, PuCl6-- and PuBr6-- show three types of bands arranged according to increasing half-width: (1) internal 5fq transitions showing a large nephelauxetic effect, the wavenumbers in the hexabromides being some 3-5 per cent smaller than of the corresponding hexachlorides; (2) 5fq→5fq-16d transitions indicating that the 5f→6d orbital energy differences are roughly constant as function of q in contrast to the strong increase in the aqua ions; (3) π245fq→π235fq+1 electron transfer bands indicating that the optical electronegativities xopt (corrected for spin-pairing energy and certain effects of L, S, J splitting) are 1·5 for U(IV), 1·75 for Np(IV) and 2·05 for Pu(IV). Further on, the charge separation effects on electron transfer bands are discussed with special regard to uranyl iodide complexes.
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