Uranium-Gallium Complex With A π Bond

A newly made complex features a uranium-gallium bond, only the second known molecule containing a bond between an actinide element and a group 13 element. Steve T. Liddle of the University of Nottingham, in England; Cameron Jones of Monash University, in Australia; and colleagues synthesized the complex in which the U–Ga bond is surrounded by the chelating ligand tris(2-aminoethyl)amine-trimethylsilane (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200805481). The molecule is also noteworthy, the authors say, because the U–Ga bond shows characteristics of π bonding, a trait that has not been seen before between an f-block element and a group 13 element. Scientists have debated the potential of f elements to bond covalently. That ability could have implications for nuclear waste separation, for example, where chemists would like to exploit the different chemistries of covalent bonding in lanthanides and actinides. The discovery comes on the heels of a report of the first actinide-group 13 complex, which contains a uranium-aluminum bond (C&EN, Aug. 4, 2008, page 36). One of that study's authors, John Arnold of the University of California, Berkeley, says the new work "adds significantly to our fundamental knowledge of f-element interactions with group 13 elements."