Ligand-centered redox processes for manganese, iron and cobalt, MnL3, FeL3, and CoL3, complexes (L = acetylacetonate, 8-quinolinate, picolinate, 2,2'-bipyridyl, 1,10-phenanthroline) and for their tetrakis(2,6-dichlorophenyl)porphinato complexes[M(Por)]

Abstract

The potentials for the ML3"/ML3 couple of MnL3, FeL3, and CoL3 complexes (L = acetylacetonate, 8-quinolinate, picolinate, 2,2'-bipyridyl, 1,10-phenanthroline) occur at substantially less positive values than those for their zinc analogues and are clearly ligand-centered. The negative shift in potential for these ligand oxidations is proportional to their metal-ligand covalent-bond energies. The reductions for the bipyridyl and phenanthroline complexes of these transition metals also are ligand-centered. Electrochemical characterization of tetrakis(2,6-dichlorophenyl)porphine and of its neutral porphinato complexes with Zn, Mn, Fe, and Co indicates that electron transfer occurs within the porphyrin ring and that the metal-porphyrin bonding involves covalent a bonds between d"sp valence electrons of the neutral metal (or hydrogen atoms of porphine) and two pyrrole p electrons of the uncharged porphyrin.

Electrodeposition of palladium from palladium(II) acetylacetonate in an amide-type ionic liquid

“…Acetylacetonate complexes have been widely used as a precursor of metal nanoparticles [18]. Electrochemical behavior of various acetylacetonate complexes in organic solvent has been also reported so far [19][20][21]. On the other hand, there are few reports about electrochemical study of acetylacetonate complexes in ionic liquids [22,23].…”

Novel Low Spin Mixed Ligand Thiohydrazide Complexes of Iron(III): Synthesis, Spectral Characterization, Molecular Modeling, and Antibacterial Activity

“…This compound presumably formed as a result of iron(III) mediated oxidation of the ligand. The standard reduction potential value of the Fe 3+/2+ changes from 0.77 V to −0.42 V (versus SHE) when it is coordinated to acetylacetonato (acac) ligand in DMF medium [25]. Thus the system loses its oxidizing property when Fe(acac) 3 is used as the precursor and the chances of metal mediated ligand oxidation is minimized.…”

The nature of the bonding between metalloporphyrins [Fe(II), Co(II), Mn(II)] and oxygen species (·O2·, H2+O·/HO·, HOO·, ·O·)

“…The iron porphyrins are important cofactors in electron-transfer enzymes and the critical component in the oxygen-binding proteins (hemoglobin and myoglobin). A recent study [2] [11,12] relative to those for (Cl 8 TPP)Fe III -OH and the reduction potential for ÁOÁ(g) (0.43 V vs SCE) [13]. Thus, the free energies of bond formation (ÀDG BF ) for these oxene adducts are estimated to be as follows: (Cl 8 …”