UC Davis

This dissertation attempts to summarize two of the author’s several research projects – in separate, broadly disparate areas of chemistry. Chapters I, II and III discuss the structural chemistry of fullerenes while chapters IV, V, VI and VII discuss metal-mediated chemistry focusing on the oxidative coupling of tertiary amines. All of the doctoral research performed during the author’s time in the Balch group is not covered in this dissertation. Instead, two representative areas of chemistry have been chosen. In Chapter I, we discuss the relationship between the shape and geometry of fullerenes, and the arduousness of their structural characterization. An elegant solution to this problem is the technique of cocrystallization, which is discussed in this chapter. Chapter II explores the use of this technique of cocrystallization in the analysis of two endohedral metallofullerenes. The two compounds are isostructural and their crystal structure is discussed in detail, paying special heed to peculiarities in porphyrin conformation. This and other variations in the nature of porphyrinfullerene association leads us to a systematic study of the phenomenon of cocrystallization, which is discussed in Chapter III. The variation in the ratio of porphyrins binding each fullerene, as well as how conformational changes in the porphyrin affects the quality of “ordering” experienced by the fullerene, is explained in this Chapter. We look at two separate parameters – metal-ion effects, and solvent/solvate effects. We do not delve into the C-C bond activation chemistry of fullerenes and the various strategies employed in the functionalization of C60, but a recent positive outcome of our efforts to synthesize a metal-inserted heterofullerene is briefly mentioned in the conclusion to Chapters I, II and III. ii Chapter IV discusses some of the various reactivity shown by titanium (IV) chloride in the coordination chemistry performed with it. Titanium (IV) chloride has been demonstrated over the course of this project to act as a halogenating agent, halogen abstraction agent, oxidizing agent, radical stabilizer (in form of a noncoordinating anion), in addition to its pedestrian role as a small, hard metal center capable of ordinary coordination chemistry. We discuss two different behaviors it exhibits towards tertiary phosphines, and then examine its behavior towards tertiary amines. Chapter V explores the direct crystallization of radical cations of amines, through oneelectron oxidation, by using titanium (IV) chloride as oxidant. This process for isolating crystalline forms of tertiary amine radicals is unprecedented. Simultaneously, we compare two other closedshell metal halides, antimony (V) chloride and tin (IV) chloride, in similar systems. All three metal halides are shown to perform direct crystallization of suitable tertiary amine radicals. However, we begin to see variation in the behavior of these metal halides in Chapters VI and VII, where we deliberately choose tertiary amines that are capable of further association to form diamines. A metal-dependent selectivity of the diamine product formed is observed. This is not only novel but also remarkably significant to the field of triarylamine-based charge transfer materials, where the nature of the π-system bridging the nitrogen centers in di- or polyamines massively influences the redox properties of the system. Our technique for metal-mediated “tuning” of the diamine product leaves room for a great deal of future work in exploiting oxidative coupling reactions for preferential formation of charged diamine species. We have also demonstrated a time-dependent product conversion that, with more refinement of kinetic control, can be established as a second metric for diamine selectivity.