Synthesis, Molecular and Electronic Structure of U<sup>V</sup>(O)[N(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>
dataset
posted on 2012-02-06, 00:00 authored by Skye Fortier, Jessie
L. Brown, Nikolas Kaltsoyannis, Guang Wu, Trevor W. HaytonAddition of 1 equiv of 2,2,6,6-tetramethylpiperidine-1-oxyl
(TEMPO)
to U(NR<sub>2</sub>)<sub>3</sub> in hexanes affords U(O)(NR<sub>2</sub>)<sub>3</sub> (<b>2</b>), which can be isolated in 73% yield.
Complex <b>2</b> is a rare example of a terminal U(V) oxo complex.
In contrast, addition of 1 equiv of Me<sub>3</sub>NO to U(NR<sub>2</sub>)<sub>3</sub> (R = SiMe<sub>3</sub>) in pentane generates the U(IV)
bridging oxo [(NR<sub>2</sub>)<sub>3</sub>U]<sub>2</sub>(μ-O)
(<b>3</b>) in moderate yields. Also formed in this reaction,
in low yield, is the U(IV) iodide complex U(I)(NR<sub>2</sub>)<sub>3</sub> (<b>4</b>). The iodide ligand in <b>4</b> likely
originates from residual NaI, present in the U(NR<sub>2</sub>)<sub>3</sub> starting material. Complex <b>4</b> can be generated
rationally by addition of 0.5 equiv of I<sub>2</sub> to a hexane solution
of U(NR<sub>2</sub>)<sub>3</sub>, where it can be isolated in moderate
yield as a tan crystalline solid. The solid-state molecular structures
and magnetic susceptibilities of <b>2</b>, <b>3</b>, and <b>4</b> have been measured. In addition, the electronic structures
of <b>2</b> and <b>3</b> have been investigated by density
functional theory (DFT) methods.
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