A new type of double uranium oxo cation [O–U–O–U–O] 4+ is prepared by selective oxygen-atom abstraction from macrocyclic uranyl complexes using either boranes or silanes. A significant degree of multiple U [Private characterDOUBLE BOND, LENGTH AS M-DASH ] O bonding is evident throughout the U 2O 3 core, but either trans-, cis- or trans-, trans-OUOUO motifs can be isolated as boron- or silicon-capped oxo complexes. Further controlled deoxygenation of the borylated system is also possible.
†Electronic supplementary information (ESI) available: Full experimental and characterisation details, and further IR spectroscopic and X-ray crystallographic data. CCDC 1812761–1812765. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8cc00341f