In situ XANES of an iron porphyrin irreversibly adsorbed on an electrode surface

In illY iron K-edge X-ray Absorption Near Edge Structure, XANES, has been employed to examine the axial coordination of~-oxobis [iron mesotetrakis (methoxyphenyl) porphyrin] (FeTMPFhO, irreversibly adsorbed on a high area carbon substrate, Black Pearl (EP), as a function 0:" the applied potential.Analysis of the XANES provides conclusive evide Ice that the coord:nation about Fe(3 +) in the supported, fully oxidized macrocycle is remarkably different from that about Fe(2+) in the corresponding fully-reduced macrocycle.In the adsorbed, oxidized state, (FeTMPPhO retains its ~xo character and it und{ rgoes a two-electron reduction to yield predominantly four-coordinate square planar FeTMPP without axial ligation.1