The chemistry of a series of para-hydroquinones substituted in the 2,5-positions with a proton accepting amine group has been investigated. The p-hydroquinones are designed with bis-bidentate coordination pockets allowing for the bridging of two metals and extended multimetallic complexes. Several aspects of the hydroquinones chemistry was examined, including the redox behaviour and properties of the hydroquinones while in their free forms, complexed to palladium and complexed to boron.
The redox properties of para-hydroquinones which contain intramolecular hydrogen bonds as indicated by X-ray structural and spectroscopic data were examined. The cyclic voltammograms of some of these hydroquinones indicated they could be oxidized reversibly to give dicationic benzoquinones. The oxidized forms have been chemically isolated and characterized for the first time. Characterization data of the dicationic benzoquinones revealed the OH protons are transferred intramolecularly to the adjacent nitrogen bases. Spectroscopic solution data for the p-benzoquinone dications suggests
that the intramolecular hydrogen bonds in the redox related p-hydroquinone are no longer present. A correlation between the oxidation potential of the 2,5-substituted-p-hydroquinone and base strength of the nitrogen substituent was shown to exist.
The bis-bidentate p-hydroquinones were coordinated to palladium resulting in dinuclear complexes. The non-innocence of the ligand was preserved upon coordination but the complexes are oxidized at more positive potentials in comparison to the analogous p-benzoquinone species. Two of the palladium complexes were chemically oxidized resulting in the semiquinone radical redox state of the ligand. The EPR and UV-vis spectroscopy of the radical p-semiquinone palladium complexes indicates their properties are similar to o-semiquinone palladium complexes.
The bis-bidentate p-hydroquinones and some related ligands were also coordinated to the main group element, boron. Cyclic voltammetry of the boron complexes revealed the redox properties of the bridging p-hydroquinone were perturbed and redox processes occurred at even more positive potentials in comparison to the analogous palladium complexes. The dinuclear boron complexes were highly fluorescent with quantum yields calculated to be in the range of 0.36-0.52. These boron complexes incorporated an uncommon ancillary ligand, acetate. The acetate ligand was found to be advantageous for the solubility and fluorescence properties for one of the boron compounds in comparison to the analogous boron complex incorporating the more commonly used fluorine ancillary ligand. / Graduate / 0490 / 0488 / 0485
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/5003 |
| Date | 29 October 2013 |
| Creators | Trefz, Tyler |
| Contributors | Hicks, Robin Gary |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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