Recent results in the chemistry of the actinides in oxidation states less than +4 will be described and compared with the latest advances in low oxidation state rare-earth metal chemistry. It is now known that the +2 oxidation state is accessible in crystallographically-characterizable molecular complexes of Th, U, Np, and Pu. Th(II) was found in (Cp"3Th)1− and U(II) in (Cp'3U)1− and (Cp"3U)1− where Cp' = C5H4SiMe3 and Cp" = C5H3(SiMe3)2. Np(II) and Pu(II) were isolated in (Cp"3An)1− complexes synthesized at Los Alamos National Laboratory in collaboration with A. J. Gaunt, S. A. Kozimor, and co-workers. Isolation of these four An(II) species allows a comparison with Ln(II) complexes which have been found to exist in three categories: traditional Ln(II) ions with 4fn+1 electron configurations, (Eu, Yb, Sm, Tm), new Ln(II) ions with 4fn5d1configurations (La, Ce, Pr, Gd, Tb, Ho, Er, and Lu), and configurational crossover Ln(II) ions that can have either configuration depending on the ligands (Dy and Nd). The new actinide complexes will be compared with the rare-earth compounds in terms of synthesis and the dependence of stability and electronic structure on the specific ligands involved. Efforts to use the low oxidation state rare-earth chemistry as a guide to low oxidation state actinide chemistry will be described as well as the development of new classes of actinide complexes with low oxidation states.

Recent advances in low oxidation state actinide chemistry

2019 Spring National Meeting

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