This thesis reports the spectroscopic and computational studies of a number of Cu(I), Re(I) and Ru(II) complexes of polypyridyl ligands. The ligands considered in this study were 1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline, dibenzo[b,j][1,10]phenanthroline, dipyrido[2,3-a:3�,2�-c]phenazine, dipyrido[2,3-a:3�,2�-c]-6,7-dichlorophenazine and dipyrido[2,3-a:3�,2�-c]-6,7-dimethylphenazine.
Density functional theory calculations were carried out on the polypyridyl ligands. Validation of the calculations was carried out by comparison of the predicted values to observables. The structures were compared to previously published X-ray crystal data. Calculated bond lengths were typically calculated to be within 0.02 Å of those in the crystal structure. The calculated vibrational spectra were compared to measured IR and Raman spectra. The correspondence between calculated and measured frequencies was quantified using the mean absolute deviation between the two sets of frequencies. This was typically found to be less than 10 cm⁻�. The robustness of the calculation was further tested by calculations on perdeuterated analogues of some of the ligands. The calculations were extended to metal moieties and validated as for the ligands.
Resonance Raman and infrared spectra of the reduced states of some Re(I) complexes are reported. The structure and spectra have been modelled by considering the radical anion of the polypyridyl ligand and the reduced state of the complex. There is improvement in the mean absolute deviation, between calculated and observed frequencies, upon incorporation of the metal moiety into the calculation. Spectra are successfully modelled confirming the validity of the modelled structures.
The resonance Raman and infrared spectra of the metal-to-ligand charge transfer excited states of some Cu(I), Re(I) and Ru(II) complexes are reported. Density functional theory calculations on the lowest energy triplet states aided in the spectral assignment of bands. Cu(I) complexes were successfully modelled with mean absolute deviations, between calculated and observed frequencies, of less than 10 cm⁻�. The spectra of the Re(I) and Ru(II) complexes were less successfully modelled. Incorporation of the Ru(II) centre into the calculation of the vibrational frequencies of dipyrido[2,3-a:3�,2�-c]phenazine complexes offers no improvement over modelling the radical anion of this polypyridyl ligand.
The excited state lifetimes of a number of polypyridyl complexes have been reported. The changes in lifetimes of similar complexes were found to be consistent with the energy gap law or changes in the conjugation of the involved polypyridyl ligand.
This project has allowed the excited state structures of a number of polypyridyl complexes to be determined using vibrational spectroscopy to validate density functional theory calculations. This has provided a study strategy that may be applied to other metal polypyridyl complexes.
| Identifer | oai:union.ndltd.org:ADTP/217480 |
| Date | January 2005 |
| Creators | Howell, Sarah Louise, n/a |
| Publisher | University of Otago. Department of Chemistry |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://policy01.otago.ac.nz/policies/FMPro?-db=policies.fm&-format=viewpolicy.html&-lay=viewpolicy&-sortfield=Title&Type=Academic&-recid=33025&-find), Copyright Sarah Louise Howell |
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