UC Irvine

This dissertation focuses on efforts to expand upon the discovery that the +2 oxidation state is available in molecular forms for all the rare earth metals, i.e. Sc, Y, and the lanthanides. In addition to the previously isolated +2 ion complexes of La, Ce, Nd, Sm, Eu, Dy, Tm, Yb, and Sc, the first complexes containing +2 ions of Y, Pr, Gd, Tb, Ho, Er, and Lu had been prepared under strongly reducing conditions with the (C5H4SiMe3)33− ligand set. This dissertation describes efforts to broaden the ligand sets available to isolate new +2 rare-earth metal ions and to study their reactivity and physical properties. Chapter 1 describes the use of (C5H5)33− and (C5H4Me)33− ligand sets to isolate more examples of Y2+ complexes, and compares their stability and properties with those of other ligand sets. For (C5H4Me)33−, reduction reactions with other rare-earth metals as well as some reactivity studies are also described. Chapter 2 describes the dinitrogen reactivity of the Y2+ species generated from the reductions of (C5H5)3Y and (C5H4Me)3Y. Chapter 3 describes the synthesis and reactivity of +2 ion complexes from the reduction of ( (C5Me4H)3Ln complexes. Chapter 4 describes the synthesis of the first crystallographically characterizable Sc2+ complex, {Sc[N(SiMe3)2]3}− including physical characterization by EPR and UV-vis spectroscopy. Chapter 5 describes the reactivity of the Sc2+ complex, [Sc[N(SiMe3)2]3}−, with dinitrogen to generate the first end-on bridging dinitrogen complex of a rare-earth metal, {[Sc[N(SiMe3)2]3]2(μ-η2:η2-N2)}2−. Chapter 6 describes additional reactivity studies of [Sc[N(SiMe3)2]3}− with carbon monoxide, carbon dioxide, and acetonitrile. Chapter 7 describes the mechanochemical synthesis of the sterically crowded complexes, (C5Me5)3Ln (Ln = Tb, Dy, Ho, Er).