Molybdenum(VI) Coordination in Tributyl Phosphate Chloride Based System

Fundamental coordination chemistry of Mo­(VI) at its macroconcentrations in solvent extraction systems is of great importance for industrial processes that require the purification or recovery of large concentrations of Mo. The coordination of Mo­(VI) in tri-<i>n</i>-butyl phosphate (TBP) from solutions of hydrochloric acid and up to 0.3 M Mo was investigated using UV, FTIR, and ³¹P NMR spectroscopies, as well as EXAFS. From these techniques we resolved near-neighbor atoms, speciation, structural information on the coordination environment, and thermodynamic parameters affiliated with the solvent extraction of Mo­(VI) and HCl. The solvated extracted form of Mo­(VI) as MoO₂Cl₂·2TBP was identified. High extraction yield of Mo at >5 M HCl concentration is driven by replacing HCl in the organic phase by Mo. The existence of additional organic Mo adducts is also discussed with the aid of density functional theory, however no evidence of dimeric or polymeric Mo species was found to be present in TBP

Trivalent Uranium Phenylchalcogenide Complexes: Exploring the Bonding and Reactivity with CS₂ in the Tp*₂UEPh Series (E = O, S, Se, Te)

The trivalent uranium phenylchalcogenide series, Tp*₂UEPh (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 ¹H 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 CS₂ insertion into the U­(III)–E bond, forming Tp*₂U­(κ²-S₂CEPh) (E = S (<b>5</b>), Se (<b>6</b>), Te (<b>7</b>)). Compound <b>5</b> was characterized crystallographically

Trivalent Uranium Phenylchalcogenide Complexes: Exploring the Bonding and Reactivity with CS₂ in the Tp*₂UEPh Series (E = O, S, Se, Te)

The trivalent uranium phenylchalcogenide series, Tp*₂UEPh (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 ¹H 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 CS₂ insertion into the U­(III)–E bond, forming Tp*₂U­(κ²-S₂CEPh) (E = S (<b>5</b>), Se (<b>6</b>), Te (<b>7</b>)). Compound <b>5</b> was characterized crystallographically