Date of Award
Doctor of Philosophy in Clinical-Bioanalytical Chemistry
College of Sciences and Health Professions
The coordination chemistry of nitric oxide (NO) with transition metals has been extensively investigated, but that of organic NO derivatives as ligands less so. Some nitrosoalkanes RNO and nitrosoarenes ArNO are in equilibrium with dimeric species known as N,N'–azodioxides, R(O)NN(O)R or Ar(O)NN(O)Ar. The cis diastereomers of azodioxides have been proposed to act as bidentate chelating ligands for both main-group and transition metals, but only three azodioxide complexes, a dicationic iron (II) complex, a neutral scandium (III) complex, and a dicationic calcium (II) complex, have thus far been structurally characterized before our work in this area. The delocalized π system of azodioxides suggests that they may be able to act as redox-active ligands. The objectives of this project are to develop further the coordination chemistry of azodioxides and to investigate their ability to behave as redox-active ligands. The first goal is the synthesis and characterization of novel azodioxide complex cations of first-row transition metals, with the diamagnetic, redox-stable counteranion hexaflurophosphate (PF6-). This synthetic strategy has yielded novel azodioxide complexes of cobalt whose structure was determined via single-crystal X-ray diffraction. Future work will involve spectroscopic and magnetic measurements of azodioxide complexes for evidence of electroisomerism, a phenomenon characterized by low-lying, thermally accessible electronic excited states arising from metal-to-ligand or ligand-to-metal charge transfer. Additionally, azodioxide complexes will be screened as potential catalysts for organic reactions such as allylic amination/ reactions of alkenes. Medicinal applications of azodioxides will also be explored by cell-based studies on cancer cells.
Balaraman, Lakshmi, "Coordination Chemistry of N,N’- Azodoxides" (2019). ETD Archive. 1168.