Amide complexes of uranium tetrahalides and uranyl chloride

Abstract

Uranium tetrachloride and tetrabromide form 1 : 2 complexes with amides of the type R¹·CO·NR²R³ when R¹ or R² and R³ are bulky branched chains (R¹= Cme³, Me₂CHCH₂, or Me₂CH with R²= R³= Me, and R¹= Me with R²= R³= Prⁱ) but form 1 : 4 complexes when R¹= Me, R²= H, and R³= Et or Prⁱ. The corresponding uranyl chloride complexes are all of composition UO₂Cl₂,2L except where L is CH₃CONHEt, when a 1 :3 complex is obtained, I.r. spectroscopic results are reported for these, and some analogous thorium tetrachloride complexes. Studies of the u.v.–visible spectra of the complexes UX₄,4L indicate that 1 :2 complexes are formed first in the reaction of the tetrahalide with the ligand and that the 1 :4 complexes react with halide ion in non-aqueous solvents to form octahedral anions [UX₅L]^– and [UX₆]^2–.