Expanding the Family of Uranium(III) Alkyls: Synthesis and Characterization of Mixed‐Ligand Derivatives

Abstract

The generation of uranium(III) alkyls supported by hydrotris(pyrazolyl)borate (Tp) and pentamethylcyclopentadienyl (Cp*) ligands is reported. Mixed ancillary ligand frameworks were synthesized by treating TpUI2(THF)3 (1) and Cp*UI2(THF)3 with potassium hydrotris(pyrazolyl)borate salts. Addition of one equivalent of potassium hydrotris(3,5‐dimethylpyrazolyl)borate (Tp*) generated TpTp*UI (2), while treatment of Cp*UI2(THF)3 with either KTp or KTp* resulted in the respective formation of Cp*TpUI(THF) (3) or Cp*Tp*UI(THF) (4). Alkylation of 2 with KCH2Ph or NaCH2SiMe3 furnished TpTp*UCH2Ph (2‐CH2Ph) or TpTp*UCH2SiMe3 (2‐CH2SiMe3). Similarly, treatment of 3 with NaCH2SiMe3 formed Cp*TpUCH2SiMe3 (3‐CH2SiMe3), whereas treatment of 4 with KCH2Ph generated Cp*Tp*UCH2Ph (4‐CH2Ph). All compounds were characterized by multinuclear NMR, IR, and electronic absorption spectroscopy. Compounds 2‐CH2Ph, 3, and 3‐CH2SiMe3 were structurally characterized using X‐ray crystallography as well.