Presentation Title

Exploring the reduction of nitrous oxide at metal centers through synthesis, spectroscopy and computations

Faculty Mentor

S. Chantal E. Stieber

Start Date

18-11-2017 2:15 PM

End Date

18-11-2017 2:30 PM

Location

9-271

Session

Bio Sciences 2

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Nitrous oxide (N2O) is the third most potent greenhouse gas with a global warming potential 310 times higher than carbon dioxide. Reducing the concentration of N2O is chemically challenging, however biological systems can reduce N2O through chemical reactions at copper centers within enzymes. Understanding the mechanism of N2O reduction would benefit pollutant control and have possible environmental significance. This project aims to explore activation modes relevant to the conversion of N2O to NO by studying the electronic and geometric structures of metal nitrosyl complexes. We investigated how metal compounds interact with NO species through synthesis, X-ray emission spectroscopy (XES) and calculations. XES probes transitions from filled valence orbitals and can be used to inform ligand identity, metal ligand bonding, and metal spin state. While XES is a sensitive probe for the identification of metal-bound ligands and the quantification of small-molecule bond activation, the method is still being developed. We have used XES in combination with computational chemistry to understand chemical interactions between NO and nickel, and to quantify NO activation and coordination modes. Currently, synthesis of Co-N2 and Co-NO complexes is underway for future XES studies. The XES development in this work offers new techniques for characterizing complex systems, understanding mechanisms of N2O reduction, and detecting NO in biological settings.

Summary of research results to be presented

We have used XES in combination with computational chemistry to understand binding modes between NO and nickel. Our results demonstrate that various binding modes of nitrosyl at nickel can be experimentally distinguished by XES. This highlights the sensitivity of XES for determining small molecule coordination to metal centers. To gain further insight into the electronic structures of the nickel nitrosyl complexes, density functional theory (DFT) calculations were carried out. The DFT-calculated XES spectra have good agreement with experiment and reveal metal-ligand interactions that contribute to resulting spectral features. Notably, the calculated XES spectra suggest that XES is sensitive to Ni-N-O bond angle changes of 10 degrees. The good correlation between experiment and theory suggests that XES can characterize small molecule intermediates in biological systems

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Nov 18th, 2:15 PM Nov 18th, 2:30 PM

Exploring the reduction of nitrous oxide at metal centers through synthesis, spectroscopy and computations

9-271

Nitrous oxide (N2O) is the third most potent greenhouse gas with a global warming potential 310 times higher than carbon dioxide. Reducing the concentration of N2O is chemically challenging, however biological systems can reduce N2O through chemical reactions at copper centers within enzymes. Understanding the mechanism of N2O reduction would benefit pollutant control and have possible environmental significance. This project aims to explore activation modes relevant to the conversion of N2O to NO by studying the electronic and geometric structures of metal nitrosyl complexes. We investigated how metal compounds interact with NO species through synthesis, X-ray emission spectroscopy (XES) and calculations. XES probes transitions from filled valence orbitals and can be used to inform ligand identity, metal ligand bonding, and metal spin state. While XES is a sensitive probe for the identification of metal-bound ligands and the quantification of small-molecule bond activation, the method is still being developed. We have used XES in combination with computational chemistry to understand chemical interactions between NO and nickel, and to quantify NO activation and coordination modes. Currently, synthesis of Co-N2 and Co-NO complexes is underway for future XES studies. The XES development in this work offers new techniques for characterizing complex systems, understanding mechanisms of N2O reduction, and detecting NO in biological settings.