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Theoretical and experimental electron paramagnetic resonance studies : A, The conformation of transition metal-biuret complexes and their interaction with carbohydrates and polyols : B, Radical anions of 9, 10 anthrasemiquinone generated by carbohydrates

A detailed review and revision of the theories required to simulate the electron paramagnetic resonance (epr) spectra of S' = 1/2 transition metal monomers and dimers is undertaken. The simulation of the epr spectrum of bis(biuretato)cuprate(II), doped in its isomorphous nickel(II) complex, enables the determination of its effective spin Hamiltonian parameters, independent of PH and solvent effects. An axial bis(biuretato)cuprate(II) dimer is also detected at 110 K and its simulated spectra indicate that it is formed by the axial interaction of two monomers. / The nature of copper(II)-biuret complexes in acidic and neutral media is then investigated. Their epr spectra are shown to be deceptively simple and arise from more than one species in solution. Furthermore, in basic media the bis(biuretato)cuprate(II) and di-(mu)-hydroxo-bis(biuretato)dicuprate(II) are the predominant species. However a consideration of the structure and superexchange interactions of the latter complex indicate that it is "epr silent". / Electronic absorption and epr investigations demonstrate that polyols and carbohydrates interact axially with bis(biuretato)cuprate(II) in solution without the displacement of the equatorial biuretato ligands. / The resonance field positions and general contribution of the g tensor to the epr intensities of a preferentially oriented paramagnetic probe is derived. They are used in simulating the epr spectra of copper(II) complexes adsorbed on cellulose fibres. The results suggest that the complexes interchelate between the cellulosic sheets of the fibre. An empirical parameter describing the degree of order of the sheets, within the fibre, is defined and estimated. / Stable 9,10-anthrasemiquinone radicals are generated by carbohydrates in strictly aqueous media for the first time. They are also shown to be the predominant radicals in AQ-Soda and AQ-Kraft-Soda pulping liquors. Monitoring the radical concentrations with temperature via epr strongly suggests that they should not be disregarded as possible catalysts in these processes.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.77145
Date January 1981
CreatorsMattar, Saba M. (Saba Mitri)
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageDoctor of Philosophy (Department of Chemistry)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 000138857, proquestno: AAINK58079, Theses scanned by UMI/ProQuest.

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