ABSTRACTJOHN R. PATTERSON Synthesis and Reactivity of Heterocyclic Thione and Selone Ligands with a Saturated Backbone (Under the direction of DR. DANIEL RABINOVICH) The field of coordination chemistry is so pervasive that it finds use in nearly every branch of chemistry. Notable examples of metal complexes include hemoglobin, high utility catalysts, cancer medicines, and precursors to bulk and nanoscale materials. Previously within the Rabinovich group, the coordination chemistry of various unsaturated N-heterocyclic thione (NHT) and selone (NHSe) ligands has been explored. Utilizing the known analogous chemistry of N-heterocyclic carbenes (NHCs), there is evidence that saturated heterocycles are better sigma donors than their unsaturated counterparts. Exploration of this concept to deduce its consistency with NHT or NHSe ligands is still necessary, however. The focus of this project has been the synthesis and reactivity of saturated five-membered N-heterocyclic chalcogenones. This work has explored the reactivity of these kinds of molecules by varying donor atom, sulfur or selenium, and the steric hindrance provided by the N-substituents. Examples of NHT or NHSe molecules with saturated backbones found in the literature lack large bulky aromatic N-groups. Research to better understand the coordination properties of these ligands has resulted in multiple experiments including synthetic, computational, spectroscopic, and crystallographic. Some coordination complexes with mercury(II), gold(I), compounds of iodine, and computational analysis has been attempted and the results will be discussed.