Synthesis, characterisation, and some properties of molecular mixed-ligand peroxo complexes of uranium(VI) containing amines or aminocarboxylic acids as coligands

Abstract

Molecular peroxo complexes of [UO₂]²⁺, viz. [UO₂(O₂)(phen)](phen = 1,10-phenanthroline), [UO₂(O₂)(bipy)](bipy = 2,2'-bipyridyl), [UO₂(O₂)(en)](en = ethylenediamine), [UO₂(O₂)(H₄edta)](H₄edta = ethylenediamine-NNN'N'-tetra-acetic acid), and [UO₂(O₂)(gly)](gly = glycine), have been synthesised at different pH values of the reaction medium. They are diamagnetic. On the basis of spectroscopic evidence, both peroxide and each of the coligands, except gly, are co-ordinated to the metal in a bidentate manner, while gly occurs in its zwitterionic form and acts as a monodentate ligand. The complex [UO₂(O₂)(gly)] oxidises triphenylphosphine, cyclohexene, styrene, and SO₂(g) to triphenylphosphine oxide, 1,2-cyclohexanediol, 1-phenylethylene glycol, and sulphate respectively.