Decomposition into higher species: Intramolecular UIII-mediated homolytic C-O bond cleavage in UIII (alkoxy)siloxy complexes at low temperature and subsequent reduction with KC8 led to unprecedented polymetallic complexes containing siloxy, silanediolate, and silanetriolate ligands (see example: U green, Si yellow, K blue, O red). Such compounds may be useful precursors to uranium ceramics relevant for catalysis and the storage of spent nuclear fuel. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.