Abstract: A central aim of synthetic f-block chemistry is to quantify the extent and nature of covalency in the bonding of these ions. When considering ways to achieve this aim, studying early actinide-ligand multiple bonding is an attractive place to start because such linkages tend to, by definition, exhibit appreciable amounts of covalency and thus they are amenable to being probed using a wide range of structural, spectroscopic, magnetic, and quantum chemical calculation techniques. Additionally, whilst of interest in their own right, early actinide-ligand multiple bonds can provide a baseline for comparisons to transuranium and lanthanide analogues; this will in turn provide a rounded picture and understanding of these ions overall, enabling contextualization of their bonding with respect to the d-transition metals as well.

This talk will describe some of our research in this area, specifically: (i) our terminal uranium-nitride work, where most importantly the above approach has enabled quantification of the covalency of this benchmark linkage; and (ii) extension of this approach to include neptunium-oxo and -imido complexes, which has revealed some fundamental similarities and differences between the behavior of uranium and neptunium.