Conditional oxidation state

Binary and ternary selenides and tellurides show essentially the same behaviour 138, 139) as the sulfides. The situation is rather special142) for the TmSe and TmTe containing, on an instantaneous picture 13) 80 or 50 percent, respectively, of the conditional oxidation state 4f12 Tm[III] and the rest (20 or 50%) 4f13 Tm[II]. 

Metallic uranium (180, 181) has a photo-electron spectrum with distinct signals, the strongest originating in the 4/, 4d and 5d shells. Most uranium(VI) compounds have similar spectra (15, 37, 181) with a modest chemical shift dl amounting to 3 to 5 eV. This behaviour is comparable to the d groups and very different from europium, where it was early shown (39) that metallic alloys containing the conditional oxidation state 4/7 Eu[II] and Eu(II) compounds such as EuSCU (15) have I of all the inner shells 10 eV lower than of the Eu(III) compounds. 

The equilibria and variety of species discussed above would seem to make studying the specific oxidation states of actinides difficult. However, through careful control of the conditions, oxidation state pure solutions for all of the actinides can be obtained for synthetic, quantitative and/or qualitative studies. 

It is possible to define the conditional oxidation state written in square brackets (75) from the number of electrons in the partly filled shell which have the distinctly smallest average radius in the system. Thus, in lanthanides contdning 4fi in the preponderant electron configuration, the conditional oxidation state is (Z —54—q). The two colmnns to the right of Table 1 correspond to M[III] and the rest of the entries in Table 1 to M[II] when no 5d electron occurs, whereas they correspond to M[IV] and M[III], respectively, when a 4f electron is replaced by a 5d... 

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