2 research outputs found
Influence of Substituents on the Electronic Structure of Mono- and Bis(phosphido) Thorium(IV) Complexes
No full textA series of metallocene thorium complexes
with mono- and bisÂ(phosphido) ligands have been investigated with
varying hues: (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ(Cl)Â[PÂ(Mes)<sub>2</sub>] (Mes = mesityl = 2,4,6-(CH<sub>3</sub>)<sub>3</sub>C<sub>6</sub>H<sub>2</sub>; dark red-purple), (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ[PÂ(Mes)Â(CH<sub>3</sub>)]<sub>2</sub> (dark red-purple),
(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ(CH<sub>3</sub>)Â[PÂ(Mes)<sub>2</sub>] (dark red-purple), (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ(CH<sub>3</sub>)Â[PÂ(Mes)Â(SiMe<sub>3</sub>)] (orange), (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ(Cl)Â[PÂ(Mes)Â(SiMe<sub>3</sub>)] (orange),
(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ[PÂ(Mes)Â(SiMe<sub>3</sub>)]<sub>2</sub> (orange), and (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>ThÂ[PHÂ(Mes)]<sub>2</sub> (pale yellow). While all of these complexes
bear a mesityl group on phosphorus, the electronic structure observed
differs depending on the other substituent (mesityl, methyl, trimethylsilyl,
or hydrogen). This sparked an investigation of the electronic structure
of these complexes using <sup>31</sup>P NMR and electronic absorption
spectroscopy in concert with time-dependent density functional theory
calculations
A Pseudotetrahedral Uranium(V) Complex
No full textA series of uranium
amides were synthesized from <i>N</i>,<i>N</i>,<i>N</i>-cyclohexylÂ(trimethylsilyl)lithium amide [Li]Â[NÂ(TMS)ÂCy]
and uranium tetrachloride to give UÂ(NCySiMe<sub>3</sub>)<sub><i>x</i></sub>(Cl)<sub>4–<i>x</i></sub>, where <i>x</i> = 2, 3, or 4. The diamide was isolated as a bimetallic,
bridging lithium chloride adduct ((UCl<sub>2</sub>(NCyTMS)<sub>2</sub>)<sub>2</sub>-LiClÂ(THF)<sub>2</sub>), and the trisÂ(amide) was isolated
as the lithium chloride adduct of the monometallic species (UClÂ(NCyTMS)<sub>3</sub>-LiClÂ(THF)<sub>2</sub>). The tetraamide complex was isolated
as the four-coordinate pseudotetrahedron. Cyclic voltammetry revealed
an easily accessible reversible oxidation wave, and upon chemical
oxidation, the U<sup>V</sup> amido cation was isolated in near-quantitative
yields. The synthesis of this family of compounds allows a direct
comparison of the electronic structure and properties of isostructural
U<sup>IV</sup> and U<sup>V</sup> tetraamide complexes. Spectroscopic
investigations consisting of UV–vis, NIR, MCD, EPR, and U L<sub>3</sub>-edge XANES, along with density functional and wave function
calculations, of the four-coordinate U<sup>IV</sup> and U<sup>V</sup> complexes have been used to understand the electronic structure
of these pseudotetrahedral complexes
