“Oxidative
Addition” of Halogens to
Uranium(IV) Bis(amidophenolate) Complexes
- Publication date
- Publisher
Abstract
A series
of U(IV) complexes, (<sup>R</sup>ap)<sub>2</sub>U(THF)<sub>2</sub> [R = <i>tert-</i>butyl (<i>t</i>-Bu)
(<b>1</b>), adamantyl (Ad) (<b>2</b>), diisopropylphenyl
(dipp) (<b>3</b>)], supported by the redox-active 4,6-di-<i>tert</i>-butyl-2-(R)amidophenolate ligand, have been synthesized
by salt metathesis of 2 equiv of the alkali metal salt of the ligand,
M<sub>2</sub>[<sup>R</sup>ap] [M = K (<b>1</b> and <b>2</b>), Na (<b>3</b>)], with UCl<sub>4</sub>. Exposure of these
uranium complexes to 1 equiv of PhICl<sub>2</sub> results in oxidative
addition to uranium, forming the bis-(4,6-di-<i>tert</i>-butyl-2-(R)iminosemiquinone) ([<sup>R</sup>isq]<sup>1–</sup>) uranium(IV) dichloride dimer, [(<sup>R</sup>isq)<sub>2</sub>UCl]<sub>2</sub>(μ<sup>2</sup>-Cl)<sub>2</sub> [R = <i>t</i>-Bu (<b>4</b>), Ad (<b>5</b>), dipp (<b>6</b>)].
The addition of iodine to <b>1</b> forms (<sup>tBu</sup>isq)<sub>2</sub>UI<sub>2</sub>(THF) (<b>7</b>), while the reactivity
of I<sub>2</sub> with <b>2</b> and <b>3</b> results in
decomposition. Complexes <b>1</b>–<b>7</b> have
been characterized by <sup>1</sup>H NMR and electronic absorption
spectroscopies. X-ray crystallography was employed to elucidate structural
parameters of <b>2</b>, <b>3</b>, <b>5</b>, and <b>7</b>
