The blood‐red plutonocene complex Pu(1,3‐COT′′)(1,4‐COT′′) (4; COT′′=η⁸‐bis(trimethylsilyl)cyclooctatetraenyl) has been synthesized by oxidation of the anionic sandwich complex Li[Pu(1,4‐COT′′)₂] (3) with anhydrous cobalt(II) chloride. The first crystal structure determination of an organoplutonium(IV) complex revealed an asymmetric sandwich structure for 4 where one COT′′ ring is 1,3‐substituted while the other retains the original 1,4‐substitution pattern. The electronic structure of 4 has been elucidated by a computational study, revealing a probable cause for the unexpected silyl group migration.

The first well-defined lanthanide polysulfide complexes containing S ₄ ²⁻ and S ₅ ²⁻ ligands have been synthesized and structurally characterized by single-crystal X-ray diffraction.

The first metallasilsesquioxanes comprising potassium and uranium have been synthesized and structurally characterized by single-crystal X-ray diffraction. (Cy₇Si₇O₁₂)₂K₆(DME)₄ (2; Cy = cyclohexyl) is a centrosymmetric dimer, in which the two silsesquioxide ligands are interconnected by μ₃- and μ₄-bridging siloxide moieties. (Cy₇Si₇O₁₂)₂U^VI (3) represents the first metallasilsesquioxane complex of an actinide element, featuring a U atom that is coordinated by two tridentate silsesquioxide ligands in a distorted octahedral fashion. The different structural effects of the large metal atomic radii are discussed.