UC Irvine

This dissertation describes the synthesis, physical characterization, and reactivity of new classes of rare earth metal complexes to explore the chemistry of the recently discovered +2 oxidation state. In each chapter, a new ligand arrangement that supports Ln2+ ions is presented with the goal of evaluating how physical properties, ground-state electron configuration, and reactivity are affected by the coordination environment. Chapters 1-3 describe Ln2+ complexes in tris(cyclopentadienyl) coordination environments. Specifically, Chapter 1 presents new heteroleptic complexes, [K(2.2.2-cryptand)][(C5H3(SiMe3)2)2LnCpR] (Ln = Y, Gd; CpR = C5H5, C5H4Me). Chapter 2 describes the homoleptic complexes, [K(2.2.2-cryptand)][(C5H3(SiMe3)2)3Ln] (Ln = La, Ce, Pr, Nd). Chapter 3 consists of a reactivity survey of the three classes of Ln2+ ions, which are defined as the traditional Ln2+ ions (Ln = Eu, Yb, Sm, Tm), the new 4fn5d1 ions (Ln = La, Ce, Pr, Gd, Tb, Ho, Er, Y, Lu) and the configurational crossover ions (Ln = Dy, Nd). Chapters 4 and 5 describe Ln2+ complexes supported by anionic arene ligands. Chapters 6-8 describe new Ln2+ complexes supported by a tris(aryloxide)mesitylene ligand; this work is a collaborative effort with the lab of Professor Karsten Meyer at the Friedrich-Alexander-Universität Erlangen-Nürnberg. Chapter 9 is a structural analysis of the base-free metallocenes (C5H3R2)2Ln (Ln = Sm, Eu; R = CMe3, SiMe3) and the mono(cyclopentadienyl) tetraphenylborate complex [C5H3(CMe3)2]Eu(μ-η6:η1-Ph)2BPh2. The goal of Chapter 9 was to test whether the tris(carbocyclic) coordination environment of (C5H3R2)Ln(μ-η6:η1-Ph)2BPh2 would allow the observation of Ln1+. Finally, Chapter 10 presents a reactivity study of the 5d1 La2+ complexes, [K(2.2.2-cryptand)][(C5H4SiMe3)3La] and [K(2.2.2-cryptand)]2[((C5H4SiMe3)2La)2(C6H6)], with diphenylacetylene.