Skip to main content
Open Access Publications from the University of California

UC Irvine

UC Irvine Electronic Theses and Dissertations bannerUC Irvine

Spectroscopic and Computational Analysis of Rare Earth and Actinide Complexes in Unusual Coordination Environments and Oxidation States

  • Author(s): Fieser, Megan E.
  • Advisor(s): Evans, William J
  • et al.

This dissertation describes the use of spectroscopic and computational methods to understand new classes of rare earth and actinide coordination complexes. In Chapters 1 and 2, the use of UV-vis spectroscopy and density functional theory (DFT) to understand a rare form of photochemical activation of rare earth mixed-ligand tris(cyclopentadienyl) complexes, (C5Me5)3-x(C5Me4H)xLn, and metallocene allyl complexes, (C5Me5)2Ln(C3H5) (Ln = Lu, Y) is described. The photochemistry involves a ligand-based reduction in a trivalent rare earth complex that generates a reducing system powerful enough to reduce dinitrogen. Chapter 3 describes the use of Raman spectroscopy to understand bond lengths in reduced dinitrogen rare earth complexes, [(C5Me5)2Ln](μ-η2:η2-N2), and analyze the degree of dinitrogen reduction based on the ancillary ligands. Chapter 4 describes the power of NMR spectroscopy to characterize complicated mixtures of heterobimetallic bridging hydride complexes, (C5Me5)2Ln(H)2Ln′(C5Me5)2, and tuckover hydride complexes, (C5Me5)2Ln(μ-H)(μ-η1:η5-CH2C5Me4)Ln′(C5Me5) (Ln, Ln′ = La, Y, Lu). DFT was used to investigate the metal site preferences in these complexes.

Chapters 5 through 10 describe different techniques to understand the first examples of molecular rare earth and actinide tris(cyclopentadienyl) complexes in the formal +2 oxidation state, [K(2.2.2-cryptant)][(C5R5)3Ln] (Ln = Y, lanthanides, Th, U). DFT is used to describe the configuration of these complexes as 4d1 for Y, [Ln3+]5d1 for 10 lanthanides and [An3+]6d1 for Th and U (Chapter 5 and 6). UV-vis spectroscopy was used to distinguish between different electron configurations of Ln2+ complexes (Chapter 7). Magnetic susceptibility measurements characterize two Ln2+ complexes to have record high single-ion magnetic moments (Chapter 8). Ligand and metal edge X-ray absorption spectroscopy were used to analyze the oxidation state of the metals (Chapter 9). Reactivity of cyclooctatetraene with Ln2+ complexes is described in Chapter 10. Chapter 11 presents the synthesis of new Ln3+ and Ln2+ complexes, using a tris(aryloxide)arene coordination environment. Chapter 12 describes the use of DFT to predict new coordination environments that could allow the stabilization of the +2 oxidation state for the rare earths and actinides.

Main Content
Current View