Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

The coordination chemistry of the diamine ligands, 2,2’-bipyridine (bipy) and 1,10-phenanthroline (phen), with d- and f-block metals has been extensively explored during the last century to yield many technological and industrial applications. Despite this long history, the chemistry of these diamine ligands in hetero-metallic systems containing multiple metals is poorly understood even to date. This study reports, for the first time, a systematic investigation into the coordination behavior bipy/phen in the hetero-metallic iron-uranium system covering all the combination of the possible redox couples (i.e. Fe2+/Fe3+ and U4+/U6+) that are potentially relevant to the actual engineered or environmental systems. In total, eleven new compounds of pure-uranium and hetero-metallic Fe-U complexes were successfully synthesized and structurally characterized. The synthesized compounds show an intriguing structural variety in terms of the nuclearity of the metal center (mono- and dinuclear for both Fe and U) and the manner of crystal packing based on different intra- and intermolecular interactions (e.g. π•••π interactions, hydrogen bonding, etc.). The results also highlight the similarity of the fundamental coordination properties of bipy and phen towards Fe and U, regardless of the oxidation states of the metals, as well as the striking dissimilarity in their chemical behavior upon crystal packing.