Correlation between gas-phase electron affinities, electrode potentials, and catalytic activities of halogenated metalloporphyrins

The gas-phase electron affinities (EAs) of a series of halogenated iron tetraphenyl porphyrins determined using ion cyclotron resonance mass spectrometry are reported. The EAs of the Fe(II) species vary approximately linearly with their condensed-phase reduction potentials. The EAs of the Fe(III) species with axial Cl ligands vary approximately linearly with condensed-phase reduction potentials. The lines for the Fe(III) and Fe(II) data sets are quite different, however, suggesting substantial solvent effects on the condensed-phase reduction process