Relationships between Electron-Transfer Rate Constants of Bis(ligated)(octaethylporphinato)iron(III) Perchlorate and the Presence of a Spin Equilibria

Article abstract of DOI:10.1021/ja00340a005

Heterogeneous electron-transfer rate constants were measured for a series of bis(ligated)iron(III) octaethylporphyrin and tetraphenylporphyrin complexes in CH2Cl2 (0.1 M TBAP).The former series of complexes exist in a spin equilibria while the latter are predominantly low spin at room temperature.Values of the magnetic moment were calculated for each complex and comparison made between this μ_eff and the k^o and E_1/2 of electron-transfer process Fe(III) ->/<- Fe(II).Both μ_eff and k^o and E_1/2 varied as a function of ligand for the complexes of (OEP)Fe(L)2⁺ClO4.Contrary to expectation, however, no substantial changes were observed in k^o as a function of spin state.This was true for comparisons of the (OEP)Fe(L)2⁺ and (TPP)Fe(L)2⁺ series as well as for intercomparisons between the high- and low-spin complexes of (OEP)Fe(L)2⁺.