Trivalent Uranium Phenylchalcogenide
Complexes: Exploring the Bonding and Reactivity with CS<sub>2</sub> in the Tp*<sub>2</sub>UEPh Series (E = O, S, Se, Te)
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Abstract
The trivalent uranium phenylchalcogenide
series, Tp*<sub>2</sub>UEPh (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate,
E = O (<b>1</b>), S (<b>2</b>), Se (<b>3</b>), Te
(<b>4</b>)), has been synthesized to investigate the nature
of the U–E bond. All compounds have been characterized by <sup>1</sup>H NMR, infrared and electronic absorption spectroscopies,
and in the case of <b>4</b>, X-ray crystallography. Compound <b>4</b> was also studied by SQUID magnetometry. Computational studies
establish Mulliken spin densities for the uranium centers ranging
from 3.005 to 3.027 (B3LYP), consistent for uranium–chalcogenide
bonds that are primarily ionic in nature, with a small covalent contribution.
The reactivity of <b>2</b>–<b>4</b> toward carbon
disulfide was also investigated and showed reversible CS<sub>2</sub> insertion into the U(III)–E bond, forming Tp*<sub>2</sub>U(κ<sup>2</sup>-S<sub>2</sub>CEPh) (E = S (<b>5</b>), Se (<b>6</b>), Te (<b>7</b>)). Compound <b>5</b> was characterized crystallographically