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 (1), S (2), Se (3), Te (4)), 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 4, X-ray crystallography. Compound 4 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 2–4 toward carbon disulfide was also investigated and showed reversible CS2 insertion into the U­(III)–E bond, forming Tp*2U­(κ2-S2CEPh) (E = S (5), Se (6), Te (7)). Compound 5 was characterized crystallographically.