UC Irvine

This dissertation describes efforts to expand the understanding of Ln(II) chemistry, particularly that of the non-traditional 4fn5d1 ions, through the synthesis and isolation of new Ln(II) species supported by bis(trimethylsilyl)amide ligands and exploration of their reactivity. Described herein is the isolation of a new series of Ln(II) complexes ligated by NR2 (R = SiMe3) ligands. These ligands were previously not thought to be capable of supporting the nontraditional lanthanide ions in the 2+ oxidation state. Following their isolation, the reaction chemistry of these [LnIINR2)3]1− complexes was investigated to provide insight into the unique reaction chemistry of non-traditional Ln(II) ions.

Chapter 1 outlines the synthesis and characterization of a new series of Ln(II) complexes [M(crypt)][Ln(NR2)3] (M = K or Rb) and describes their spectroscopic properties as they relate to electron configuration. Chapter 2 discusses the synthesis of the elusive [YII(NR2)3]1− complex in addition to reactions of [Ln(NR2)3]1− with CO. Chapter 3 describes new examples of uranium in the +2 oxidation state isolated by reduction of Cptet3U (Cptet = C5Me4H) and U(NR2)3 (R = SiMe3) in the presence of 2.2.2-cryptand to produce [K(crypt)][Cptet3U] and [K(crypt)][U(NR2)3], respectively. Chapter 4 expands the understanding of lanthanide-based dinitrogen reduction chemistry through discovery of the first end-on Ln2(μ-η1:η1-N2) complexes. The formation of end-on versus the more common side-on Ln2(μ-η2:η2-N2) complexes was possible by using the Ln(II) complexes detailed in Chapters 1 and 2. Chapter 5 details the reaction chemistry of the [Gd(NR2)3]1− complexes with toluene and the isolation of a methylcyclohexadienyl dianion. Chapter 6 discusses the reaction chemistry of [Gd(NR2)3]1− with BiPh3 and PPh3 and the formation of a rare example of a complex containing a Ln−Bi bond.