Ligand-centered electron-transfer redox processes for manganese, iron, and cobalt complexes in relation to selected catalytic systems /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | The oxidation potentials for a series of MnL₃, FeL₃, and CoL₃ complexes [L= acetylacetonate, 8-quinolinolate, picolinate, 2,2'-bipyridine, and 1, 10-phenanthroline] have been determined by cyclic voltammetry. The oxidations of these complexes occur at substantially less positive potentials than those for their zinc analogues and are clearly ligand-centered. The removal of an electron from the valence shell of the ligand-centered. The removal of an electron from the valence shell of the ligand is facilitated by the formation of a metal (d-electron)-ligand (p-electron) covalent bond. The negative shift in oxidation potential for a ligand is proportional to the metal-ligand covalent bond energy. The X-ray absorption edge energies for a series of manganese complexes have been determined and correlated with the electrochemical results. A change in the sp covalency of manganese (d⁵sp à d⁴sp²) corresponds to a shift of 4.3 eV, and the formation of a d-p covalent bond from a ligand-centered oxidation to a shift of 2.3 eV per bond formed. The direct conversion of cyclohexane to cyclohexanone via ion-induced activation of dioxygen species has been investigated. The addition of hydrogen peroxide to a solution that contains bis(picolinato) iron (II) and cyclohexane in a pyridine/acetic acid solvent (2:1 mole ratio) results in the direct transformation of cyclohexane to cyclohexanone. Other hydrocarbon substrates are transformed to ketones via the oxygenation of a methylenic carbon. Acetylenes and arylolefins are deoxygenated to α-dicarbonyls and aldehydes. A μ-dioxygen binuclear iron picolinate intermediate appears to be the active form of the catalyst. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xv, 130 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |