Francesca Lombardi ’24
Synthesis and characterization of d-block metal complexes containing redox-active ligands
Francesca Lombardi ’24, Chemistry major
Faculty Mentor: Dr. Maria Carroll, Chemistry and Biochemistry
Poster Presentation: Wednesday, April 24, 11 a.m. – 12:30 p.m.
The presence of CO2 in the atmosphere is a major contributor to global warming. A possible way to combat this issue is to develop a catalyst that is capable of reducing CO2 and preventing its negative effects on the environment. CO2 levels can also be lowered by replacing fossil fuels with renewable green fuels like H2 gas. Transition metal complexes are of interest in catalyzing the reduction of CO2, as well as the production of H2. We propose that iron complexes with redox active α-diimine and iminopyridine ligands can be tuned electronically to be selective for the reduction of protons or CO2by adjusting the ability of the ligand to store electrons. We began by synthesizing a series of α-diimine and iminopyridineligands with varying substituents and reacting them with zinc chloride. Coordination of the ligands to zinc was confirmed by single crystal X-ray diffraction. These molecular structures were used to analyze bond lengths as the substituents of the ligands were changed. Cyclic voltammetry experiments show that the zinc complexes undergo a single reversible redox event. We then targeted iron tricarbonyl complexes, with their ligands showing a range of reduction potentials. We developed two synthetic methods for the α-diimine and iminopyridine iron tricarbonyl complexes. These complexes were characterized by 1HNMR & 13CNMR and infrared spectroscopy along with single crystal X-ray diffraction. The electronic properties of the complexes were also analyzed using CV, and complexes exhibit a single reversible reduction. We are currently exploring the reactivity of the tricarbonyl complexes with CO2 and acid, along with the effect of increasing electron richness by reduction and substitution of carbonyl ligands with more electron rich ligands.
