Turning Ligands on Their Side: Computational Investigation into the Binding of N2O and N2 in Transition Metal Complexes

Author

Cole Donald, Stephen F Austin State UniversityFollow

Date of Award

12-2022

Degree Type

Thesis

Degree Name

Master of Science in Natural Science

Department

Chemistry and Biochemistry

First Advisor

J. Brannon Gary, Ph.D.

Second Advisor

Brian Barngrover, Ph.D.

Third Advisor

Russell J. Franks, Ph.D.

Fourth Advisor

Alyx Frantzen, Ph.D.

Fifth Advisor

Christopher Aul, Ph.D.

Abstract

Common greenhouse gas nitrous oxide (N₂O) is a thermodynamically potent and environmentally benign oxidant, making it a desirable target for metal center activation. Unfortunately, N₂O is a poor ligand for transition metals due to its weak sigma-donating and pi-accepting properties; as a result, few transition metal complexes capable of interacting with N₂O have been found. As the primary source of all nitrogen in organisms, abundant gas dinitrogen (N₂) is a crucially important tiny molecule and an essential part of daily existence. However, due to its inertness, it has limited practical uses in this form. Through biological and commercial nitrogen fixation processes, one of the most inert substances, N₂, is transformed into an accessible nitrogen supply, such as NH₃, that may be incorporated into all nitrogen-containing biomolecules. Using computational chemistry, this work will highlight the energy differences between new potential N₂O binding modes. Insights into the comparison between the k-N and k-O versus the newly reported n²-NN and n²-NO binding modes will be discussed. Through the utilization of density functional theory, a low valent cobalt complex possessing N₂O in a n²-NO coordination is reported. These binding mode comparisons can be employed to develop N₂O as a "green" oxidant given the limited understanding of the coordination of N₂O to metal centers. This study will emphasize the energy disparities between putative N₂ binding mechanisms using computational chemistry. It will also be explored how the k-N binding mode compares to the infrequently reported n²-NN binding mode. Given the partial knowledge of N₂'s coordination to metal centers, these binding mode comparisons can be used to improve understanding of N₂'s activation.

Repository Citation

Donald, Cole, "Turning Ligands on Their Side: Computational Investigation into the Binding of N2O and N2 in Transition Metal Complexes" (2022). Electronic Theses and Dissertations. 484.
https://scholarworks.sfasu.edu/etds/484

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.