High-Valent f-Element Imidophosphorane Complexes: Electronic Structure and Reactivity
Author(s)
Rice, Natalie Tate
Advisor(s)
Editor(s)
Collections
Supplementary to:
Permanent Link
Abstract
Traditionally, lanthanides exist mostly in the trivalent state in solution with a few exceptions: some divalents (samarium, europium, thulium, ytterbium) and one tetravalent (cerium). Praeseodymium and terbium were predicted to be the next most readily oxidizable lanthanides (+3.2 and +3.1 V vs. NHE, respectively) after cerium, but before 2019 were only known to exist purely in a few extended solid systems. This thesis chronicles the development of imidophosphorane ligand frameworks that stabilize the tetravalent state in molecular lanthanide complexes. These ligand frameworks enabled the isolation of incredibly reducing Ce3+ ions and enabled the isolation of one of the first molecular complexes of Tb4+ and the in-situ spectroscopic characterization of a Pr4+complex. The electronic structure and reactivity of these tetravalent complexes is thoroughly interrogated and compared.
This endeavor had unique implications for uranium which 1) is known to participate in covalent bonding more than the lanthanides due to the greater radial extent of the 5f orbitals in comparison to the 4f and 2) to exhibit a wider range of available oxidation states (+2 to +6). Significantly stabilizing the high-valent oxidation states of uranium enabled two-electron oxidative atom/group transfer to arrive at hexavalent uranium complexes that feature metal ligand multiple bonds by utilizing the U4+/U6+ couple, the least common two electron pathway at uranium.
Sponsor
Date
2021-05-01
Extent
Resource Type
Text
Resource Subtype
Dissertation