Synthesis and Characterization of Three Homoleptic Alkoxides of Uranium: [Li(THF)]2[UIV(OtBu)6], [Li(Et2O)][UV(OtBu)6], and UVI(OtBu)6

Skye Fortier, Guang Wu and Trevor W. Hayton*
Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106
Inorg. Chem., 2008, 47 (11), pp 4752–4761
DOI: 10.1021/ic800067k
Publication Date (Web): April 16, 2008
Copyright © 2008 American Chemical Society
* To whom correspondence should be addressed. Email: hayton@chem.ucsb.edu.

Abstract

Abstract Image

Addition of 6 equiv of LiOtBu to a THF/Et2O solution of UCl4 at −25 °C generates [Li(THF)]2[U(OtBu)6] (1) in 61% yield. 1 is soluble in polar organic solvents and is stable for several days in THF. However, 1 slowly decomposes in benzene or hexanes, forming the dinuclear uranium(IV) species [Li(THF)][U2(OtBu)9] (2) as one of the decomposition products. Alternatively, 2 can be directly prepared in moderate yield by the addition of 4.5 equiv LiOtBu to UCl4 in hexanes/THF at room temperature. The decomposition of 1 has been studied by 1H and 7Li{1H} NMR spectroscopies to elucidate the nature of this transformation. Oxidation of 1 occurs readily in the presence of 0.5 or 1 equiv of I2 to give [Li(Et2O)][U(OtBu)6] (3) and U(OtBu)6 (4), respectively, in good yields. Alternately, 3 can be generated by comproportionation of 1 and 4. 1−4 have been fully characterized, including analysis by X-ray crystallography. In the solid-state these complexes possess large U−O−Cq bond angles, suggestive of a significant U−O π interaction. In addition, we have studied the redox properties of 4 by cyclic voltammetry.

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History

  • Published In Issue June 02, 2008
  • Article ASAPApril 16, 2008
  • Received: January 14, 2008

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