Making, Breaking, and Elucidating Uranium-Nitrogen Multiple Bonds
Redox active ligands have proven to be versatile frameworks for transition metals due to their ability to support low-valent metals in a variety of oxidation states.1 Our laboratory has demonstrated such ligands are effective at mediating organometallic and multi-electron transfer reactions at low-valent uranium centers. Recently, we have synthesized tetravalent uranium complexes with reduced pyridine(diimine) ligands.2 The electrons stored in these ligands facilitate multi-electron reactivity, enabling the synthesis of unprecedented uranium imido [U(NR)x] complexes with unique electronic structures. Accordingly, these results will be contrasted with attempts to generate these unique species in the absence of the redox-active ligand. Independent syntheses have been developed for new imido complexes with no ancillary ligands.3,4 Overall, these species show loading imido substituent on a single metal center results in very activated U=N bonds. Full characterization of the multiply bonded species, including interesting structural parameters, will also be discussed.
Figure 1. Trends in U=N Bonds in a Family of Uranium Imido Species.
[1] De Bruin, B.; et al., Inorg. Chem. 2000, 39, 2936-2947.
[2] Anderson, N. H.; et al., Nat. Chem. 2014, 6, 919-926.
[3] Anderson, N. H.; et al., Angew. Chem., Int. Ed. 2015, 54, 9386-9389.
[4] Anderson, N. H.; et al., Nat. Chem. 2017, 9, 850-855.