Ligand-Centered Electron-Transfer Redox Processes for Manganese, Iron, and Cobalt Complexes in Relation to Selected Catalytic Systems.

摘要

The oxidation potentials for a series of Manganese L3, Iron L3 and Cobalt L3 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 care clearly 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. Other hydrocarbon substrates are transformed to ketones via the oxygenation of a methylenic carbon. Acetylenes and arylolefins are dioxygenated to alpha-dicarbonyls and aldehydes. A micron-dioxygen binuclear iron picolinate intermediate appears to be the active form of the catalyst. Keywords: Oxidation reduction reactions; Electrical measurement; Measurement. (JG)