Synthesis and structural study of new metallasilsesquioxanes of potassium and uranium

Abstract

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.