Hexahalides, actinide

Further studies of the spectra of the trivalent actinide hexahalide complexes are being carried out and will be presented in greater detail later. 

The ground state of [UOClj] has a closed-shell configuration (5f ) where HOMO/LUMO character is dominated by Cl 3p states (HOMO-2, HOMO-1, HOMO), while the unoccupied states are dominated by U 5f orbitals (LUMO, LUMO-i-1, LUMO-i-2, LUMOh-3). Higher states are a mixture of U, Cl, and O orbitals. The computed Cl K-edge spectra in Figure 12.11 shows two prominent features 2821 eV (Cl Is —U 5f) and 2822.5 eV (Cl Is U 5f+Cl 3s + O 2p) that are distinct from the [UClg] complex. The Cl Is —> U 6d + Cl 3s/3p transitions are split into two peaks one at 2824 eV and a second (shoulder) at 2826 eV. These are similar in nature to the analogs in the actinide hexahalide complexes and are also located in the same position in the spectrum. On the whole, the spectra... 

Table VII. Crystal-Field Parameters for Hexahalide 5f -Actinide Ions.

Attempts to interpret the spectra of the penta- and hexahalides of the actinides have been published, but the results should be considered preliminary only U(v) and Np(viX both Sf, have been analyzed in any detail. The magnitude of the spin-orbit interaction is known for U VI. Its free-ion spectrum has been interpreted in terms of a coupling constant, Csr= 7173.9 cm based on a... 

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