A diuranium carbide cluster stabilized inside a C<sub>80</sub> fullerene cage.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30013067.
- Also identified by DOI 10.1038/s41467-018-05210-8 and PMC identifier 6048043.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Unsupported non-bridged uranium-carbon double bonds have long been sought after in actinide chemistry as fundamental synthetic targets in the study of actinide-ligand multiple bonding. Here we report that, utilizing I<sub>h</sub>(7)-C<sub>80</sub> fullerenes as nanocontainers, a diuranium carbide cluster, U=C=U, has been encapsulated and stabilized in the form of UCU@I<sub>h</sub>(7)-C<sub>80</sub>. This endohedral fullerene was prepared utilizing the Krätschmer-Huffman arc discharge method, and was then co-crystallized with nickel(II) octaethylporphyrin (Ni<sup>II</sup>-OEP) to produce UCU@I<sub>h</sub>(7)-C<sub>80</sub>·[Ni<sup>II</sup>-OEP] as single crystals. X-ray diffraction analysis reveals a cage-stabilized, carbide-bridged, bent UCU cluster with unexpectedly short uranium-carbon distances (2.03 Å) indicative of covalent U=C double-bond character. The quantum-chemical results suggest that both U atoms in the UCU unit have formal oxidation state of +5. The structural features of UCU@I<sub>h</sub>(7)-C<sub>80</sub> and the covalent nature of the U(f<sup>1</sup>)=C double bonds were further affirmed through various spectroscopic and theoretical analyses.