Synthesis, crystal structure and dynamic behaviour in solution of monocyclooctatetraene uranium alkoxides

Abstract

Treatment of [U(cot)(BH₄)₂](cot =η-C₈H₈) with ROH (R = Et, Prⁱ or Bu^t) led to successive formation of the alkoxide derivatives [U(cot)(BH₄)(OR)]4 and [U(cot)(OR)₂]5. Their structure and dynamic behaviour in solution have been studied by NMR spectroscopy; complexes 4 are monomeric in tetrahydrofuran whereas 5 are dimeric in this solvent and monomeric in pyridine. Rapid stereoselective exchange occurs between the terminal propoxide ligands of [{U(cot)(OPrⁱ)(µ-OPrⁱ)}₂] and free PrⁱOH. The crystal structures of [{U(cot)(BH₄)(µ-OEt)}₂] and [{U(cot)(OPrⁱ)(µ-OPrⁱ)}₂] have been determined.