Faculty Mentor: Abby O’Connor
Students: Chris Bregna
One of the driving forces in the field of organometallic chemistry is catalysis, where a catalyst is defined as an additive substance that allows a chemical reaction to occur by lowering its barrier to activation. Nickel, a relatively inexpensive metal found in high abundance in the Earth’s crust, has been shown to catalyze many chemical reactions. An area where nickel complexes have not been utilized effectively is for hydrogenation reactions. Typically hydrogenation reactions are catalyzed by noble metals such as platinum, rhodium, and ruthenium, however due to the high cost and rarity of these noble metals, nickel is a cheaper alternative. Nickel has been used as a heterogeneous catalyst in hydrogenation reactions, where a heterogeneous catalyst is not found in the same phase as the reactants. On the other hand, homogenous catalysis is the process where the catalyst is found in the same phase as the reactants. A benefit of homogeneous catalysis is that the mechanism can be studied using basic spectroscopic techniques to gain insight into the reaction and aid in future catalytic design. This field is of broad interest as chemists search for new ways to design more sustainable processes as well as increase specificity in chemical reactions. The purpose of this work is to gain a deeper understanding of nickel complexes for use as homogenous hydrogenation catalysts through the synthesis and characterization of new nickel complexes containing a pendent hemilabile arene group to aid in stabilization during catalysis. This moderate coordination strength of the hemilabile group is extremely important due to the reversible binding of different species to the catalyst during the course of the reaction. Progress towards the synthesis of the allyl bromide ligand (1) and preliminary results focused on reactions of the ligand with nickel are described. Future work will focus on isolation of the new nickel complex (2) and to study its behavior in hydrogenation reactions.