Synthesis Isolation And Characterization Of Endohedral Metallofullerenes PDF Download

The following dissertation represents three fullerene related projects covered in five chapters. Two species of endohedrals will be described. The first example represents classic metallofullerenes and contains free, cationic samarium(II). The second species can be further divided into two categories: one contains metallic clusters composed of scandium(III) coordinated to either oxygen or nitrogen; the second contains metallic clusters composed of gadolinium(III) coordinated to nitrogen. Single crystal X-ray diffraction was used for elucidation of fullerene solid-state properties. Nickel(II) octaethylporphyrin was used to aid in crystallization of pristine empty and endohedral fullerenes. Solvent molecules, such as benzene, toluene, and chlorobenzene, are typically incorporated into the crystalline lattice. This can also aid in crystal growth but is not always free from disorder with in the lattice. The fullerene cage, as well as its contents, is not immune to disorder. Another typical situation encountered while performing an X-ray diffraction experiments is weakly diffracting, small, twined crystals. Our labs solution to these issues has involved synchrotron irradiation and advanced refinement techniques. Some solid-state properties of fullerene co-crystals reflect their inherent chemical nature, such as rapid molecular motion of encapsulated clusters appearing as disorder of these internal metal complexes. The introduction explores the chemical nature and stability of the prototypical fullerene: C60. The discussion is extended to how this classic model is modified when considering addends and endohedral fullerenes. All arguments consider the relevant theoretical and experimental literature. Chapter 1 focuses on optimization of various endohedral fullerene yields with Kratschmer-Huffman generators. Here, a new separation technique is described for enriching fullerene soot with typically low yielding endohedral fullerenes. Chapter 2 explores gadolinium trimetallic nitride fullerenes, with specific attention given to isolated pentagon rule (IPR) violating Gd3N@C[subscript s](39663)-C2 and its relation to the IPR obeying Er2@C[subscript s](6)-C82. I also propose a mechanism by which Gd3N@C[subscript s](39663)-C82 could mutate to Gd3N@C[subscript s](51365)-C84 with the addition of two carbons. The endohedral Gd3N@D3(19)-C86 is also reported in this chapter. Chapter 3 discusses the generation, isolation and characterization a new family of related scandium oxide cluster fullerenes: Sc4([mu]3-O)3@I[subscript h] C80, Sc4([mu]3-O)2@I[subscript h] C80, Sc2([mu]2-O)@C[subscript s](6)-C82. I compare crystallographic and computational results, but with the intent of defining the fullerenes' respective HOMO/LUMO levels in addition to predicting the more thermodynamically and entropically favored fullerene. Chapter 4 details a new class of sulfide-bridged metallic cluster fullerenes: Sc2([mu]2-S)@C[subscript s](6)-C82, and Sc2([mu]2-S)@C[subscript 3v](6)-C82. I report the structure of the fullerenes and (similarly to the scandium oxide cluster fullerenes) explain the observed species of scandium sulfide cluster fullerenes relative to thermodynamic and entropic effects. Chapter 5 relates select fullerenes (D[subscript 5h](1)-C90, C1(30)-C90, C1(32)-C90, D[subscript 3d](1)-C96, La2@D5(450)-C100, and Sm2@D[subscript 3d](822)-C[subscript 104]) from our crystallographic library to nanotubes and poses the question, "When does a fullerene stop being a fullerene?" The chapter contains crystallographic and computational results, with attention given to the orientation and stoichiometry of the fullerene to nickel(II) octaethylporphyrin. Electron density plots of the various C90 molecules and nickel(II) octaethylporphyrin are also considered. Emphasis is placed on the end-caps of carbon nanocapsules, which exist in a realm between fullerenes and nanotubes.