Includes bibliographical references. / A number of spectroscopic techniques consisting of infrared, Raman ultraviolet and 1H-nmr spectroscopy have been used in the structural analysis of square planar Pt(II) complexes.

Includes bibliographical references. / Metal-nitrogen stretching vibrations in Co(II), Ni(II), Cu(II) and Zn(II) chloride 4-methylaniline complexes are assigned by ¹⁵N-labelling in conjunction with a consideration of the relative crystal field stabilizition energies of the metal ions. Bands in the ultraviolet electronic spectra of Cu(II) β-ketoenolate complexes are more conclusively assigned by comparison of the spectra of the β-ketoenolates, their sodium salts and the copper complexes. The effect of ligand substitution on the infrared spectra of Cu(II) benzoylacetanilide complexes and their methanol adducts is used to assign copper-oxygen stretching frequencies. The effect of ligand substitution on the ultraviolet electronic spectra is used to estimate the extent of π-interaction in these complexes. The infrared spectra of six ¹⁵N-labelled Co(II), Ni(II), Cu(II) and Zn(II) N-salicylideneanthranilate complexes yield assignments of metal-ligand and certain ligand vibrations. These assignments are supported by observing the effects of metal ion and ligand substitution on the spectra. The shifts observed in the metal-ligand stretching frequencies are related to the relative crystal field stabilization energies of the metal ions and to the electron releasing and withdrawing capacities of the ligand substituents. Assignments of metal-ligand vibrations in the infrared spectra of Ni(II) and Cu(II) benzoylbenzilidenehydrazone complexes and Co(II), Ni(II), Cu(II) and Zn(II) benzoylsalicylidenehydrazone complexes are made by observing the effects of metal ion and ligand substitution on the spectra. The infrared spectra of three ¹⁵N-labelled Ni(II), Co(II) and Cu(II) triarylformazan complexes yield assignments of metal-ligand and certain ligand vibrations. The effect of ligand substitution on the infrared spectra of Ni(II) triarylformazan complexes is related to the electron releasing or withdrawing capacities of the substituents. A total of 168 complexes, of which 131 have not previously been reported, has been synthesized and discussed.

Includes bibliographical references. / An investigation of a series of imidazole complexes of first transition metal (II) nitrates, perchlorates and halides is reported. Deuteration of the imidazole ring provides reliable assignments for the internal vibrations of imidazole. This technique also permits unambiguous assignments of the internal vibrations of nitrate or perchlorate by their lack of deutero-sensitivity. The infrared spectra of imidazole and its complexes are examined in order to determine the ratio vD/ vH for bands as signed to the C-H, N-H and ring modes of the heterocyclic ring. With very few exceptions, vD/vH falls within the ranges 0. 74 to 0. 84 and 0. 93 to 1. 00 for C-H and ring vibrations, respectively. The potential usefulness of the results is discussed. Assignments of the M-N and M-halide vibrations are based on the results of the deuteration studies, metal ion substitution and on halogen substitution. The number of M-L vibrations in the far-infrared satisfies the selection rules for the molecular point or site group symmetries and facilitates accurate structural assignments.

Bibliography: p. 181-184. / The aqueous solution conformation of SAH and SAM has been investigated using lanthanide probes. SAH at pH 7.0 interacts normally with lanthanide aquo ions and lanthanide-EDTA complexes via coordination at the carboxyl group. The conformation of the homocysteine fragment is found to, be extended but bent back towards the adenine base. SAM does not interact with lanthanide aquo ions in the pH region 2-7. It does form complexes with lanthanide-EDTA species via an ion-pairing mechanism rather than direct coordination. In addition to lanthanide probes, 250 MHz 1H n.m.r. spectra yielded vicinal JHH coupling constants from which the ribose conformation in both SAM and SAH could be more accurately determined.

Bibliography: pages 133-139. / The extensive series of cyclopentadienyl transition metal complexes known, has made of interest the corresponding chemistry of pentamethylcyclopentadienyl transition metal derivatives, and other substituted cyclopentdienyl species. In the study two synthetic routes are described for the synthesis of new halomethyl complexes of molybdenum, tungsten and iron.

Bibliography: pages 143-148. / A number of spectroscopic techniques consisting of ultraviolet, ¹H-NMR and mass spectrometry have been used in the structural analysis of square planar Pt(II) complexes. The complexes trans-[PtBr₂(Y) (R-an)] (Y = C₂H₄,CO; R-an = substituted aniline) were prepared and investigated by the spectrosopic techniques. Infrared assignments were aided by isotopic labelling studies. The discussion of the two series of complexes are based on their relation to one another. The complexes trans-[PtX₂ (CO) (L)] (X = Cl, Br; L = aniline, pyridine N-oxide, pyridine, ammonia, imidazole and pyrazole) were prepared from their corresponding ethylene analogues. Infrared assignments, with labelling studies, are given for the complexes. The bonding effects in these complexes were studied using ¹H-NMR and ultraviolet spectroscopy. The ¹H-NMR spectra reveal that there is a fluxional behaviour of the ligands in some of the complexes. Hence, cold temperature studies were required to "freeze out" this fluxional behaviour and observe the expected signals due to the ¹⁹⁵pt-H coupling. The electronic effects are different when the ligand, L, was capable of forming σ-bonds with Pt²+, compared to when L was capable of forming both a- and π-bonds with Pt²+. The mass spectra show the M+ peak and subsequent fragmentation in the complexes. The fluxional behaviour of imidazole in trans-[PtX₂(C₂H₄) (Him)] was monitored by cold temperature studies. Using band shape analysis (with the aid of a computer) the activation paramaters for the exchange processes were determined. The dependence of the imidazole proton signals on temperature, solvent and excess ligand, all indicate that an intermolecular exchange process is occurring. Studies on the complex trans-[PtX₂(C₂H₄) (pyz)] and the effect of solvent on the complexes are being pursued, and it is hoped that an understanding of the role of the solvent in the exchange process will become apparent.

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The efficient utilization of O2 for oxidative chemical transformations remains an unmet challenge of the scientific community. O2 activating enzymes, however, have developed multiple strategies for controlling the reduction of O2 and harnessing its oxidative capabilities for oxidation reactions. These enzymes can serve as blueprint in the development of O2 activating catalysts for C-H bond oxidation reactions. We have developed a velvut vivum catalyst that mimics the O2 activation pathway of the nonheme iron 2-oxo-glutarate (a-KG) dependent oxygenase enzymes. Presented herein are mechanistic and spectroscopic studies of the model complex [FeII(N2O1)(a-KG)(L)] (N2O1 is 2-((2-(dimethylamino)ethyl)(methyl)amino)-acetate). Low-temperature stopped-flow UV/Vis spectroscopy was utilized to study the kinetics of the reaction of [FeII(N2O1)(a-KG)(L)] with O2 in methanol at -85 C and determine the activation energies associated with each step in the O2 activation process for comparison to computational studies. Magnetic circular dichroism (MCD) spectroscopy was used to probe the changes in ground and excited state energy levels of [FeII(N2O1)(L)3] as a result of binding a-KG or other a-keto acids. This study will allow for a better understanding of the role of a-keto acid binding in the O2 activation process and how the HOMO-LUMO energy gap of the a-keto acid might modulate the kinetics of the reaction with O2. A combination of continuous wave-electron paramagnetic resonance spectroscopy (cw-EPR) and electron spin echo envelope modulation (ESEEM) spectroscopy were utilized to determine the number of geometric isomers of [FeII(N2O1)(a-KG)(L)] in solution and the geometric configuration of the isomers detectable by EPR. These studies will ultimately be utilized to determine the isomer of [FeII(N2O1)(a-KG)(L)] that has the lowest kinetic barrier to the reaction with O2.

The underlying focus of this work has been to acknowledge the effects of anions in transition metal-based systems. In this respect, a novel family of weakly coordinating anions (imadazolylphenyl or IMP anions) in addition to traditional anions were compared under both thermal and photochemical conditions. A significant portion of this work has also been employing and analyzing computational techniques in transition metal-based systems for developing luminescent materials. In the second chapter, development of [(Ipr)Au(NCMe)]+ [IMP-H] catalytic system to deliver a mild condition for internal alkyne hydration reaction was developed. Studies on the roles of solvents, temperature, and substrate into the mechanism were accomplished through rate and kinetic isotope effect experiments. In the third chapter, a series of ion pairs in metal-based systems featuring [Ru(bipyridine)3]2+ and non-metallic systems featuring [HN(Et)3]+ were synthesized to dissect and specifically study the ion pairing vs ion coordination effects. NMR and DFT studies were performed to investigate and model those results. The Ru-based ion pairs were also employed to showcase the crucial nature of anions in light mediated E/Z isomerization reaction of an activated alkene proceeding through energy transfer pathway. In the fourth chapter, computational and photophysical studies of anionic NHC-based systems using Cu were performed. TDDFT studies to predict the energies of the singlet and triplet excited states to rationalize the luminescent properties of synthesized the complexes were attempted. In the fifth chapter, a collaboration between the Chemical Development (CD) unit of GSK at Upper Providence (PA) and Dobereiner lab (Temple University) to develop and optimize the conditions for a palladium catalyzed allylic amination reaction was undertaken. A systematic study on the roles of solvent, ligand loadings, and additives was conducted using High Throughput Experimentation, HPLC, and LCMS facilities at the GSK site. / Chemistry