Date of Award
Campus Access Thesis
Master of Science (MS)
The unique electronic properties of non-innocent ligands have attracted increasing interest of inorganic chemists in recent years. In contribution to this field of interest this dissertation investigates properties of the 8-oxyquinolate ligand at d6 transition metal centers and its role in complex redox chemistry of classical ruthenium(II) polypyridyl and rhenium(I) tricarbonyl frameworks. Following an introduction to the concept of noninnocent ligands in Chapter 1, Chapter 2 focusses on the ruthenium(II) polypyridyl complexes [Ru(bpy)2(R-OQN)]+ (where bpy = 2，2’-bipyridine, OQN = 8-oxyquinolate, and R = 2-Me; 5,7-Me2; 5-F; 5-Cl; 5,7-Cl2; 5-NO2). Non-innocent character of the Ru(d)−R-OQN(π) bonding interaction is established via computational analysis and charge delocalization across this metallorganic π-ring system is investigated using a combination of electrochmical (cyclic voltammetry) and spectroscopic techniques. UVvis-NIR and EPR spectroelectrochemical analysis has indicated substantial hole delocalization onto the R-OQN ligand following one-electron oxidation of the hybrid Ru(R-OQN) based HOMO level with redox and EPR data aligning very well with substituent Hammett parameters. Furthermore, of interest to potential application in dyesensitized solar cell devices, the panchromatic MLCT electronic absorption characteristics of these systems are maintained while concurrently tuning complex oxidation potentials. Subsequently, Chapter 3 focusses on the dimeric [fac-Re(ROQN)(CO)3]2 and monomeric [fac-Re(R-OQN)(CO)3(CH3CN)] complexes (where R=unsubstituted; 2-Me; 5,7-Me2; and 5-F) have been prepared and investigated by a similar suite of electrochemical and spectroscopic methods. It is shown that solvolysis of the dimeric complex yields the monomeric acetonitrile complex. To improve the product yield, the monomeric complex was produced directly in acetonitrile followed by the addition of triflic acid to induce precipitation from aqueous solution. The crystal structure of [fac-Re(F-OQN)(CO)3](µ-Cl)[fac-Re(F-HOQN)(CO)3]·CH3C6H5 shows evidence for a potential reaction intermediate during formation of the [fac-Re(R-OQN)(CO)3]2 dimers. Both the dimeric and monomeric complexes were characterized by UV-vis, 1H-NMR, FTIR, DFT/TD-DFT, elemental analysis, fluorescence emission, cyclic voltammetry and single crystal X-ray crystallography.
Zhao, Helen Cuiyun, "An Investigation of 8-Oxyquinolate Non-Innocence in d6 Transition Metal Complexes" (2013). Graduate Masters Theses. 198.