Chalcogen Atom Transfer
to Uranium(III): Synthesis and Characterization of [(R<sub>2</sub>N)<sub>3</sub>U]<sub>2</sub>(μ-E) and [(R<sub>2</sub>N)<sub>3</sub>U]<sub>2</sub>(μ‑η<sup>2</sup>:η<sup>2</sup>‑S<sub>2</sub>) (R = SiMe<sub>3</sub>; E = S, Se, Te)
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Abstract
Addition of 0.0625 equiv of S<sub>8</sub> to U(NR<sub>2</sub>)<sub>3</sub> (R = SiMe<sub>3</sub>) in Et<sub>2</sub>O generates
[(R<sub>2</sub>N)<sub>3</sub>U]<sub>2</sub>(μ-S) (<b>1</b>), which can be isolated in moderate yield by crystallization from
cold Et<sub>2</sub>O. Interestingly, if the U(NR<sub>2</sub>)<sub>3</sub> starting material is contaminated with the U(IV) metallacycle
U(<i>C</i>H<sub>2</sub>SiMe<sub>2</sub><i>N</i>SiMe<sub>3</sub>)(NR<sub>2</sub>)<sub>2</sub>, then a second product
is also formed in the reaction with S<sub>8</sub>, namely, [(R<sub>2</sub>N)<sub>3</sub>U]<sub>2</sub>(μ-η<sup>2</sup>:η<sup>2</sup>-S<sub>2</sub>) (<b>2</b>). This species can be separated
from <b>1</b>, in low yield, by virtue of its insolubility in
Et<sub>2</sub>O. Finally, addition of 0.5 equiv of E (E = Se, Te)
to U(NR<sub>2</sub>)<sub>3</sub> (R = SiMe<sub>3</sub>) results in
the formation of [(R<sub>2</sub>N)<sub>3</sub>U]<sub>2</sub>(μ-E)
(E = Se (<b>3</b>), Te (<b>4</b>)) in moderate yields.
Complexes <b>1</b>–<b>4</b> were fully characterized,
including analysis by X-ray crystallography
