Expanding the Chemistry of Actinide Metallocene Bromides. Synthesis, Properties and Molecular Structures of the Tetravalent and Trivalent Uranium Bromide Complexes: (C5Me4R)2UBr2, (C5Me4R)2U(O-2,6-iPr2C6H3)(Br), and [K(THF)][(C5Me4R)2UBr2] (R = Me, Et)

Abstract

The organometallic uranium species (C5Me4R)2UBr2 (R = Me, Et) were obtained by treating their chloride analogues (C5Me4R)2UCl2 (R = Me, Et) with Me3SiBr. Treatment of (C5Me4R)2UCl2 and (C5Me4R)2UBr2 (R = Me, Et) with K(O-2,6-iPr2C6H3) afforded the halide aryloxide mixed-ligand complexes (C5Me4R)2U(O-2,6-iPr2C6H3)(X) (R = Me, Et; X = Cl, Br). Complexes (C5Me4R)2U(O-2,6-iPr2C6H3)(Br) (R = Me, Et) can also be synthesized by treating (C5Me4R)2U(O-2,6-iPr2C6H3)(Cl) (R = Me, Et) with Me3SiBr, respectively. Reduction of (C5Me4R)2UCl2 and (C5Me4R)2UBr2 (R = Me, Et) with KC8 led to isolation of uranium(III) “ate” species [K(THF)][(C5Me5)2UX2] (X = Cl, Br) and [K(THF)0.5][(C5Me4Et)2UX2] (X = Cl, Br), which can be converted to the neutral complexes (C5Me4R)2U[N(SiMe3)2] (R = Me, Et). Analyses by nuclear magnetic resonance spectroscopy, X-ray crystallography, and elemental analysis are also presented.

Keywords

• trivalent and tetravalent uranium
• bromide
• organometallic