Interaction of (phthalocyaninato)iron(II) with molecular oxygen: Synthesis and characterization of two different crystalline forms of (?-oxo)bis((phthalocyaninato)iron(III))

The interaction of (phthalocyaninato)iron(II) with molecular oxygen leads to the formation of two different crystalline forms of a dimeric ?-oxo species containing an Fe-O-Fe system. Infrared and visible (reflectance and solution) spectra, X-ray powder patterns, magnetic measurements, and chemical behavior suggest that the two crystalline forms differ in the Fe-O-Fe bond angles as well as in the relative arrangement of the two phthalocyanine subunits within the dimeric molecule, ultimately resulting in different crystal lattice arrangements. These two ?-oxo forms appear to be the first well-characterized Fe(III) complexes derived from the phthalocyanine molecule. The redox behavior of the Fe(II) and Fe(III) derivatives of phthalocyanine is discussed in terms of the donor basicity of the axially ligated solvent molecules and of the ?-bonding properties of the phthalocyanine ring.