Date of Award
Doctor of Philosophy
John F. Turner
David C. Baker, Engin Serpersu, Ziling Xue, Janice Musfeldt
Inorganic chemistry encompasses a variety of topics and in many ways, these advances affect a wider sphere of chemists than purely inorganic and progress in this field is interesting to many scientists. The developments presented in this dissertation are significant as they affect three issues: catalytic reactivity, ligand fluxionality, and catalyst development. Catalysis affects industrial profit, pharmaceutical development, agrochemical synthesis, spectroscopy, enzymatic activity, and polymerization.
Progress in certain areas such as the [Cp*Rh(TsDPEN)] (TsDPEN = p-toluenesulfonyldiphenylethylenediamine) has lead to a moiety that is a powerful and efficient catalyst for the reduction of C=N bonds. The precise mechanism of the reaction has been illuminated through a combination of isolation and detection of key intermediates in the catalytic cycle, independent synthesis under non-catalytic conditions, isotopic labeling in combination with in situ 2-dimensional VT NMR. The intermediacy of a fugative Rh-H is strongly supported, and the 16 electron species [Cp*(p-toluenesulfonyldiphenylethylenediamido)Rh] also appears to play a role, implying that there is more than one mechanistic cycle that is important. Understanding this catalyst cycle explains and predicts the stereospecific reductive ability of this catalyst.
Improvement upon the understanding of the fluxional structure of polycyclic tetramines in solution allows for a better knowledge of how these species will act as ligands in solution. They are an interesting ligand-type that is likely to bind with unusual properties to a metal center. A series of these molecules were measured and modeled using 1D and 2D VT NMR spectroscopy. Correlations with the electronic structure, using group theoretical methods, supported by density functional calculation, lead to a full picture of the behavior of these proton sponges in solution.
Amido ligands, when complexed to transition metals have been the subject of intense interest in recent years and have been shown to promote new and unusual reactivity. This chemistry is often a result of both s and p donation to the metal center. In order to understand this bonding scheme and the donation involved, as well as to study the reaction chemistry, several novel amido complexes, containing both p basic and non-basic ligands, have been synthesized. The ligands and their zirconium complexes have been characterized extensively using both 2D and VT NMR techniques. The synthesis and characterization of a series of metal carbazolyl complexes by X-ray and NMR techniques is reported.
Bragg, Megan Taliaferro, "Structural and Spectroscopic Studies of Transition Metal Organometallic and Coordination Complexes with Reference to Catalysis. " PhD diss., University of Tennessee, 2005.