Redox-active ligand uranium complexes for approaches to multi-electron chemistry

<p>While transition metal complexes are known to participate in multi-electron redox chemistry to facilitate important organometallic transformations, actinides, due to their low redox potentials, have a propensity to perform single electron chemistry. Because of its highly reducing nature, the ability to control the electronics of low-valent uranium is highly sought after as this may lead to unprecedented reactivity. Our lab has specifically been interested in mediating multi-electron transformations at uranium by employing redox-active ligands. Redox-active ligands can be used to facilitate multi-electron processes such as oxidative addition and reductive elimination at single metal centers. Using primarily 2,6-((Mes)N=CMe)2C5H3N) ( MesPDIMe) as a redox-active ligand, highly reduced uranium species bearing bulky cyclopentadienyl-based ancillary ligands, CpxU (MesPDIMe)(L) (x = P (1-(7,7-dimethylbenzyl)), * (1,2,3,4,5-pentamethyl); L = THF, HMPA), have been synthesized. These species have the ability to perform one, two, and four electron reduction of a variety of substrates. For examples, uranium mediated pinacol coupling of carbonylated substrates as well as oxidative addition toward two (X2, PhE-EPh, PhE-X) and four electron (Ar-N=N-Ar’, oxygen-atom transfer reagents) organic oxidants have been studied. with both radical and concerted addition pathways operable. Synthesis of a <em>trans</em>-dioxo species, Cp*UO2(MesPDIMe), has allowed for the study of the activation of the robust U=O double bonds—providing key insights into the necessary components for U=O bond scission. The lessons learned from the reductive silylation of this complex redox-active ligand species has allowed for application of these principles to simple UO 22+ systems.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Year

2016

Author dc:creator

• Kiernicki, John J.

Contributors dc:contributor

• Suzanne C. Bart
• Mingji Dai
• David R. McMillin
• Tong Ren

• Pure sciences
• Redox-active ligands
• Uranium
• Chemistry
• Inorganic Chemistry

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/955

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-2172