Macrocyclic Polycation Complexes for Secondary Anion Binding, Molecular Recognition and Catalysis
Abstract
For the Co(2)-BISDIEN systems it was previously found that a tribridged dinuclear Co(2) complex of the macrocyclic ligand BISDIEN, in which hydroxide, dioxygen (as peroxo), and oxalato anions are bound simultaneously to both metal centers, undergoes a facile redox reaction in which the dioxygen is reduced to water and the oxalate is oxidized to carbon dioxide. This work was later extended to the study of tribridged dicobalt-BISDIEN complexes containing bound dioxygen (as bridging peroxo) and bridging catecholate and disulfocatecholate as reducing substrates. The bifunctional reductants in these systems undergo two-electron oxidation, while the four-electron reduction of dioxygen to water is accomplished by conversion of the Co(2) centers to the inert dinuclear Co(3)-BISDIEN complex. This study has now been extended to catalytic systems involving four-electron reduction substrates. Thus mesoxalate (ketomalonate) is converted entirely to carbon dioxide by the loss of four electrons, while the dioxygen is reduced to water, and the metal centers remain as cobalt(2). The system proved to be catalytic, and several turnovers were observed in the presence of excess mesoxalate. For the binulcear Cu(1) macrocyclic complexes, earlier work by this research group demonstrated that dioxygen is complexed and activated by a dinuclear Cu(1) tetra Schiff base macrocyclic ligand, resulting in oxygen insertion (hydroxylation) into a benzene ring of the macrocyclic ligand.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 07, 1992
- Accession Number
- ADA246690
Entities
People
- Arthur E. Martell
Organizations
- Texas A&M University