| This thesis describes a detailed study of the reactivity of Ru(OEP)(RR{dollar}spprime{dollar}S){dollar}sb2{dollar} complexes (where OEP {dollar}equiv{dollar} the dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin, R {dollar}equiv{dollar} methyl, ethyl or decyl, and R{dollar}spprime{dollar} {dollar}equiv{dollar} methyl or ethyl) with O{dollar}sb2{dollar}, in various solvents.; Exposure to O{dollar}sb2{dollar} (or air) of a benzene, toluene or methylene chloride solution containing PhCOOH and Ru(OEP)(RR{dollar}spprime{dollar}S){dollar}sb2{dollar} at ambient conditions, results in the selective oxidation of the axial ligand(s) on the metalloporphyrin complex to the corresponding sulfoxide(s). For a CD{dollar}sb2{dollar}Cl{dollar}sb2{dollar} solution containing {dollar}approx{dollar}20 mM of Ru(OEP)(dms){dollar}sb2{dollar} (dms {dollar}equiv{dollar} dimethylsulfide) and {dollar}approx{dollar}12 mM PhCOOH, exposed to 1 atm of O{dollar}sb2{dollar} at room temperature, {dollar}sp1{dollar}H-nmr analysis shows that most of the Ru(OEP)(dms){dollar}sb2{dollar} has oxidized to Ru(OEP)(dmso){dollar}sb2{dollar} over a period of 35h. Three detected intermediates are identified as Ru(OEP)(dms)(dmso) (where s indicates S-coordination of the sulfoxide), Ru(OEP)(dms){dollar}sb2{dollar} {dollar}sp+{dollar}PhCOO{dollar}sp-{dollar} and Ru(OEP)(dms)(PhCOO).; On the basis of detected intermediates and their properties, a "three-stage" mechanism is proposed for the O{dollar}sb2{dollar}-oxidation of the thioether ligands of Ru(OEP)(RR{dollar}spprime{dollar}S){dollar}sb2{dollar} in acidic organic media.; In the presence of excess thioether, solutions of Ru(OEP)(RR{dollar}spprime{dollar}S){dollar}sb2{dollar} in CH{dollar}sb2{dollar}Cl{dollar}sb2{dollar}, benzene or toluene, containing PhCOOH, catalyze the O{dollar}sb2{dollar}-oxidation of thioether to sulfoxide, but light above 480 nm is required.; A kinetic analysis of the gas uptake data showed that, under the experimental conditions used, the initial rate approached a maximum value for (Ru) {dollar}sb{lcub}rm o{rcub} >{dollar} 2 mM, (O{dollar}sb2{dollar}) {dollar}>{dollar} 0.14 M, and (PhCOOH) {dollar}>{dollar} 54 mM, with the limiting rate being imposed by the complete absorption of the incident light by the reaction solution. The results of a kinetic modelling analysis suggest that the photoexcited state that gives rise to the observed photochemistry has a minimum lifetime of 10{dollar}sp{lcub}-8{rcub}{dollar} s (in the absence of O{dollar}sb2{dollar}), and that Ru(OEP)(Et{dollar}sb2{dollar}S)(Et{dollar}sb2{dollar}SO), which accumulates as the concentration of Et{dollar}sb2{dollar}SO builds up, is outside of the catalytic cycle. (Abstract shortened by UMI.)... |
