Uranium halide complexes stabilized by a new sterically demanding tripodal tris(N-adamantylamidodimethylsilyl)methane ligand

The new tris(N-adamantylamine-dimethylsilyl)methane HC{SiMe₂N(H)Ad}₃ (Ts^AdH₃, 1) and its trilithium salt [HC{SiMe₂N(Li)Ad}₃] (Ts^AdLi₃, 2) were synthesized and characterized by multinuclear NMR and IR spectroscopy, elemental microanalysis, and single-crystal X-ray diffraction (XRD). The utility of 2 as a ligand transfer reagent for uranium was examined by targeting Ts^Ad-uranium(IV) and (III) complexes via its reaction with UCl₄ and UI₃(THF)₄; however, the crystalline material isolated, [U(Ts^Ad)(Cl)(μ-Cl){Li(THF)₃}] (4) and [U(Ts^Ad)U(I)] (5), are products of lithium chloride inclusion and uranium disproportionation/ligand redistribution, respectively, and hints at the wide scope of reactivity accessible to Ts^Ad-uranium complexes. Complex 5 was also independently synthesized stepwise in good yield from 2 via treatment with UCl₄ and, subsequently, Me₃SiI. The uranium complexes were characterized by a combination of NMR and IR spectroscopy, elemental microanalysis, magnetometric methods, and single-crystal XRD.