New advances in the chemistry of uranium amide compounds

The chloroamide complexes U (NEt2)(4-x)Cl-x (x = 1, 2) were obtained by comproportionation of UCl4 and U(NEt2)(4). The novel protonolysis reaction of a metal-amide bond with an acidic ammonium salt proved to be an efficient and convenient synthesis of cationic compounds. Thus were synthesized a series of metallo-organic and organometallic uranium cations in the oxidation states +3, +4, +5. The cationic amide compounds were valuable precursors of new derivatives, as they reacted with anionic reagents, acidic substrates and unsaturated molecules to give the addition, substitution and insertion products; in particular, such reactions were useful for the synthesis of monocyclooctatetraene uranium compounds. The dialkyl amide ligand was found able to stabilize the +5 oxidation state of uranium; neutral and cationic uranium(Ti) complexes were obtained by oxidation of their corresponding anionic and neutral U(IV) precursors. (C) 1998 Elsevier Science S.A. All rights reserved.