First characterization of an uranium(III) complex with a carbonyl-containing ligand: Syntheses and X-ray crystal structures of the homoleptic dimethylformamide complexes [M(dmf) n]I 3 (M = Ce, Nd and n = 8; M = La, Ce, U and n = 9)

Abstract

Solutions of the trivalent iodides LnI 3 and [UI 3(py) 4] in dimethylformamide (dmf) deposited crystals of the tricationic species [M(dmf) n ]I 3 (M = Ce ( 1), Nd ( 2) and n = 8; M = La ( 3), Ce ( 4), U ( 5) and n = 9). The dmf ligands are labile and easily removed under vacuum affording solid samples of [MI 3(dmf) n ] compounds with varying numbers of coordinated dmf molecules ( n = 2–6). The uranium derivative was oxidized into [U(dmf) 9]I 4 in dmf at 110 °C. X-ray crystal structures of complexes 1– 5 show the differences between the U–O and Ln–O distances to reflect the variation in the ionic radii of the metals, demonstrating the similar nature of the [M]–O C interaction in these series of 4f- and 5f-elements.