Synthesis of lanthanide compounds for the evaluation of structural features of bent metallocenes, factors in terbium luminescence, and effect of charge on mono and dicationic divalent lanthanide species

The lanthanide metals have special properties which make them a unique series of elements. These properties are important in developing fundamental aspects of science as well as industrial applications. This dissertation describes synthetic and structural studies which address both fundamental and applied aspects of lanthanide chemistry. The first part of this dissertation describes the development of a series of divalent, bimetallic mixed metallocenes containing both C₅Me₅ and C₈H₈ ligands which provide information on a theoretical problem involving the structure of organometallic compounds. This problem exists because one of the most extensively studied organolanthanide compounds, (C₅Me₅)₂Sm, has a bent structure in the solid state unlike transition metal sandwich complexes. Although several of theories have been proposed to account for the bending, there is no consensus on its origin. The bimetallic complexes described here, as well as a series of trivalent mono-metallic mixed metallocenes were synthesized to obtain more data on this problem. X-ray crystallography showed that all of these new complexes were bent and the bending is a function of ionic radii rather than ligand environment. The bimetallic complexes were also found to exhibit the ability to do unusual two electron reductions and the results of these studies are reported.; The second part of this dissertation describes a series of new, luminescent terbium compounds. The luminescent properties of the lanthanides, especially europium and terbium, make them important components of phosphors. Despite the importance of these compounds, synthetic methods for the generation of terbium complexes directly from the metal were not known. These compounds were prepared by reactions of terbium metal activated by small amounts of mercury salts with arylalcohols in isopropanol. They were then used to examine the phenomenon of metal-metal luminescent quenching to see how Tb-Tb distances affected emission in fully characterized systems.; The third part of the dissertation involves cationic lanthanide compounds. Although cationic organometallic complexes are of much interest due to their importance in processes such as Ziegler-Natta polymerizations, few cationic complexes of the lanthanides are known. Cationic divalent compounds are particularly rare although they offer the unusual combination of the increased electrophilicity due to the formal positive charge and the ability to act as a reducing agent. To fill this void, general routes to these systems have been developed. Reactions of mono and bis(amide) complexes of the divalent lanthanides with alkylammonium reagents provide access to a number of mono- and dicationic lanthanide complexes including, [Yb(THF)₆]2+, [Sm(THF) ₇]2+, [Yb(MeCN)₈]2+ and [{lcub}Zr ₂(OiPr)₉{rcub}Yb(THF)₂]+, which were isolated at [BPh₄]− salts.; In the final part of this dissertation, the synthesis and characterization of two new (C₅R₅)₃Ln systems are presented as well as preliminary reactivity studies. Compounds of the general formula (C₅Me₅)₃Ln were once thought to be too sterically crowded to exist. Recent developments in synthetic techniques have allowed for the reactivity of these unusual species to be studied as a function of the size of the metal. The (C₅Me₅)₃Ce and (C₅Me₄H)₃Lu systems are described here.