Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.)--Virginia Commonwealth University, 2010. / Prepared for: Dept. of Chemistry. Title from title-page of electronic thesis. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, 1920. / "Private edition, distributed by the University of Chicago libraries, Chicago, Illinois." "Reprinted from the Physical review, n.s., vol.xviii, no. 6, December, 1921." Also available on the Internet.

Report (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 53-61). Also available via the Internet.

No description available.

In this thesis, the preparation of a number of halomethyl complexes of rhodium, platinum, and palladium is described. Complexes of the type trans-[Rh(CH2X)X(P4)]+ (X = Cl, Br, I, P = PMe3, dmpe) were found to be unstable, decomposing in situ to give a mixtures of dihalo, trihalo, and phosphine ylide species. Platinum and palladium species of the type trans-M(CH2X)X(PEt3)2 (X = Cl, I, M = Pt, Pd), which were formed by the reaction between M(PEt3)3 CH2XY were also unstable. In the case of platinum, phosphine ylide species were isolated from reaction mixtures, whilst the palladium halomethyl species decomposed over a number of days to give dihalide complexes. However, palladium iodomethyl species prepared via reactions involving 2 moles of phosphine per mole of metal were found to be stable. Neutral rhodium halomethyl complexes were also found to be far more stable than their cationic counterparts. The synthesis and characterisation of trans-RhCl(CO)(CH2l)I(P)2/ (P = PMe3, PEt3, or Et2PPh), prepared by oxidative addition of CH2I2 to RhCl(CO)(P)2 is described. When less basic phosphines (such as PPh3) or the sterically hindered phosphine PCy3 were used, no evidence of any reaction between the rhodium complex and the CH2I2 was observed. The molecular structure of trans-RhCl(CO)(CH2l)I(PEt3)2 has been studied by X-ray diffraction analysis. This complex proved to be inert to substitution at the iodomethyl carbon atom by neutral nucleophiles such as H2O, CH3OH, and PEts, but prone to substitution by Cl-. The lability of iodomethyl (and chloromethyl) ligands towards CO insertion has also been studied. There is evidence to suggest that an iodoacyl platinum complex may form in solution after the complex cis-Pt(CH2l)I(PPh3)2 had been left under 1 atm CO for 24 hours. However, in the case of trans-Pd(CH2l)I(PCy3)2 this same reaction took 7 days under 70 atm pressure of CO. All of the rhodium iodomethyl complexes prepared were also inert to CO insertion at ambient temperature and 1 atm CO, but excellent evidence for CO insertion having taken place in irflns-RhCl(CO)(CH2l)I(PEt3)2 was observed at 70°C and 35 atm of CO. Evidence for CO insertion into a rhodium-chloromethyl bond was also observed under the more forcing conditions of 100°C and 70 atm CO. This insertion reaction may prove to be extremely useful in catalytic systems. A report of some preliminary catalytic studies involving the production of diethylmalonate from CH2I2 and C2-products from the hydroformylation of (CH2O)[sub]n under very mild conditions is also presented. It is thought that these catalytic reactions proceed via carbonyl insertion into a rhodium-iodomethyl bond.

1. É relatado estudo sistemático da extratibilidade de complexos mistos de metais de transição com haletos, pseudohaletos e trifenilfosfina, arsina, estibina, sob condições variadas, com diversos solventes, mostrando as tendências gerais de comportamento das espécies envolvidas. Dessa ampla abordagem derivam algumas possibilidades de aplicações analíticas que são desenvolvidas. 2. A presença de cianeto impede a formação e destrói alguns complexos de paládio do tipo acima referido, fato que conduziu à elaboração de uma prova de toque para este íon. Papel convenientemente preparado, contendo complexo de paládio, é descorado por HCN desprendido de amostras contendo cianeto, possibilitando a identificação de 0,3 µg de CN. Na presença de interferentes, algumas modificações de procedimento tornam o teste praticamente específico. 3. A partir de soluções aquosas contendo o ácido hacloroplatínico (IV), soluções benzênicas de trifenilestibina somente extraem o produto organometálico na presença de iodeto e não de brometo ou cloreto. As condições para uma extração seletiva e subsequente determinação espectrofotométrica de iodeto são indicadas, assim como as tolerâncias para outros íons estranhos. O método elaborado permite identificar iodeto na faixa de concentração de 6 - 24 ppm na diluição final, sendo a medida espectrofotométrica efetuada em 385 nm. 4. O complexo diazido-bis(trifenilfosfina)-paládio (II), em solução benzênica, reage com monóxido de carbono dando o isocianeto complexo correspondente, com mudança das características espectrais região do ultravioleta próximo. Com base nesta reação, mostra-se que possível a determinação espectrofotométrica de monóxido de carbono misturas gasosas com teores 700 - 3000 ppm. / Abstract not available.

No description available.

The adsorption of iodine on a platinum(111) single-crystal surface has been investigated using LEED, Auger spectroscopy, and work function measurements. The phase transformations and work function changes have also been measured during desorption. Mass spectroscopy shows that above 300 K the main desorption product is atomic iodine with a small amount of molecular iodine detected as well. The desorption kinetics at these temperatures were studied by different techniques to extract the kinetic parameters and the orders of the desorption reactions. There are two main desorption features, one displaying zero-order desorption kinetics typical of a phase transition and the other displaying first-order kinetics with a coverage-dependent activation energy. The work function changes during adsorption and desorption were shown to be a function of coverage rather than having a site dependence. The adsorption of iodine at temperatures below 200 K was also studied. Multilayers of molecular iodine are formed that desorb with essentially zeroth order kinetics. Two multilayer desorptions were observed with thermal desorption spectroscopy. One of the multilayer desorptions had a significant work function change associated with it. The work function changes were modelled by calculating the hybridization dipole moment using extended-Hückel theory with Bloch wavefunctions. The calculations are sensitive to the atomic position of the adsorbate and require further refinement. Due to the protective nature of the iodine layer and its high polarizability, the iodine layers were used to study the ambient pressure adsorption of fluorinated carbosilane dendrimers. These dendrimers are stable in vacuum but do not form an ordered structure at ambient temperature. Heating the adsorbed dendrimer in vacuum to 1100 K produced a new ordered structure on the platinum surface. This structure was shown not to be an intact dendrimer molecule as two different dendrimers with similar structural moieties produced the same (√19x√19)R23.4° LEED pattern. The ordered structure was studied by Auger spectroscopy to determine the carbon coverage. This structure is proposed to be islands of a coincidental lattice of graphite. / Graduate

The voltammetric behaviour of I-cysteine and other organic compounds such as hydrazine, hydroxylamine and methionine has been studied on GCE modified with phthalocyanine complexes of osmium, rhodium and ruthenium. For cysteine oxidation, the catalytic activity of the electrode was dependent the nature of the axial ligand. When cyanide and dimethylsulphoxide (DMSO) were used as axial ligands, giving (DMSO)(Cl)Rh(III)Pc, [(CN)₂Rh(III)Pc], (DMSO)₂0S(II)Pc and [(DMSO)₂Ru(II)Pc].2DMSO complexes, the peak current increased with repetitive scanning, indicating the increase in catalytic activity of the electrode after each scan. This behaviour was not observed when pyridine was used as axial ligand. The improvement of the catalytic activity of the GCE after the first scan has been attributed to the formation of the dimeric π-cation radical species at the electrode surface. Water soluble phthalocyanine complex ([(CN)₂Os(II)Pc]²⁻) and the tetramethyltetra-pyridinoporphyrazine complexes of Pd(II) and Pt(II), ([Pd(II)2,3Tmtppa(-2)]⁴⁺, [Pd(II)3,4Tmtppa(-2)]⁴⁺, [Pt(II)2,3Tmtppa(-2)]⁴⁺ and [Pt(II)3,4Tmtppa(-2)⁴⁺) have been prepared. [(CN)₂Os(II)Pc]²⁻ is soluble in water at pH greater 4 without the formation of dimers. The [M(II)Tmtppa(-2)]⁴⁺ (M = Pd or Pt) show high solubility in water and are stable only in acidic pHs. The cyclic voltammetry of the MPc and [M(II)Tmtppa(-2)]⁴⁺ complexes prepared, is also reported. The interactions of amino acids I-histidine and I-cysteine with the [M(II)Tmtppa(-2)]⁴⁺ complexes of Pd(II) and Pt(ll) were studied. All the [M(Il)Tmtppa(-2)]⁴⁺ are readily reduced to the monoanion species [M(Il)Tmtppa(-3)]³⁻ in the presence of histidine and cysteine. The rate constants for the interaction of [M(Il)Tmtppa(-2)]⁴⁺ complexes ofPt(II) and Pd(II), with histidine and cysteine range from approximately 2 x 10⁻³ to 0.26 dm³ mol⁻¹ s⁻¹. Kinetics of the interaction of [Co(Il)TSPc]⁴⁻ with amino acids, histidine and cysteine in pH 7.2 buffer were studied. The rate constants were found to be first order in both [Co(II)TSPc]⁴⁻ and the amino acid. The formation of [Co(III)TSPc]³⁻ in the presence of histidine occurred with the rate constant of 0.16 dm³ mol⁻¹ s⁻¹, whereas the formation of the [Co(I)TSPc]⁵⁻ species in the presence of cysteine gave the rate constant of 2.2 dm³ mo⁻¹ s¹. The relative quantum yield (QΔ) for singlet oxygen production by [(CN)₂Os(Il)Pc]²⁻, and [(CN)⁴Ru(II)Pc]²⁻ in DMF using diphenylisobenzofuran (DPBF) and a chemical quencher were determined. The quantum yield values were obtained as 0.39 ± 0.05 , and 0.76 ± 0.02 for [(CN₂Os(II)Pc]²⁻ and [(CN)₂Ru(II)Pc]²⁻ respectively. The differences in quantum yield values have been explained in terms of donor abilities of both the central metal and the axial ligands.