Efficient, one-step scalable syntheses of uranium hexamethoxide, U(OCH3)6, starting from readily available UF6 and NaOCH3 or CH3Si(OCH3)3 are described. In addition, the reaction of appropriate quantities of (CH3)3SiOCH3 or U(OCH3)6 with UF6 produces a series of mixed methoxyuranium(VI) fluorides, U(OCH3)nF6-n = 1-5, the degree of substitution being determined by control of stoichiometry. Characterization of the complexes by both and 19F NMR indicates that all the species possess a monomeric, six-coordinate geometry and undergo rapid, intermolecular ligand exchange. A surprisingly large solvent and temperature dependence of the 19F chemical shifts is interpreted in terms of charge-transfer complex formation. The solution-phase electronic spectrum of U(OCH3)6 is interpreted in terms of both ligand- and solvent-to-metal charge transfer.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry