Transition-metal-bridged bimetallic clusters with multiple uranium–metal bonds

Heterometallic clusters are important in catalysis and small-molecule activation because of the multimetallic synergistic effects from different metals. However, multimetallic species that contain uranium-metal bonds remain very scarce due to the difficulties in their synthesis. Here we present a straightforward strategy to construct a series of heterometallic clusters with multiple uranium-metal bonds. These complexes were created by facile reactions of a uranium precursor with Ni(COD)2 (COD, cyclooctadiene). The multimetallic clusters' cores are supported by a heptadentate N4P3 scaffold. Theoretical investigations indicate the formation of uranium-nickel bonds in a U2Ni2 and a U2Ni3 species, but also show that they exhibit a uranium-uranium interaction; thus, the electronic configuration of uranium in these species is U(III)-5f26d1. This study provides further understanding of the bonding between f-block elements and transition metals, which may allow the construction of d-f heterometallic clusters and the investigation of their potential applications.