Control of Oxo-Group Functionalization and Reduction of the Uranyl Ion

Uranyl complexes of a large, compartmental N8-macrocycle adopt a rigid, “Pacman” geometry that stabilizes the UV oxidation state and promotes chemistry at a single uranyl oxo-group. We present here new and straightforward routes to singly reduced and oxo-silylated uranyl Pacman complexes and propose mechanisms that account for the product formation, and the byproduct distributions that are formed using alternative reagents. Uranyl(VI) Pacman complexes in which one oxo-group is functionalized by a single metal cation are activated toward single-electron reduction. As such, the addition of a second equivalent of a Lewis acidic metal complex such as MgN″2 (N″ = N(SiMe3)2) forms a uranyl(V) complex in which both oxo-groups are Mg functionalized as a result of Mg−N bond homolysis. In contrast, reactions with the less Lewis acidic complex [Zn(N″)Cl] favor the formation of weaker U−O−Zn dative interactions, leading to reductive silylation of the uranyl oxo-group in preference to metalation. Spectroscopic, crystallographic, and computational analysis of these reactions and of oxo-metalated products isolated by other routes have allowed us to propose mechanisms that account for pathways to metalation or silylation of the exo-oxogroup.

URI

http://hdl.handle.net/10454/9499

Version

Accepted manuscript

Citation

Arnold PL, Pécharman AF, Lord RM, Jones GM, Hollis E, Nichol GS, Maron L, Fang J, Davin T and Love JB (2015) Control of Oxo-Group Functionalization and Reduction of the Uranyl Ion. Inorganic Chemistry. 54 (7): 3702−3710.

Link to Version of Record

https://doi.org/10.1021/acs.inorgchem.5b00420

Type

Article