Structural and Physical Characterization of (Nitrato)iron(III) Porphyrinates [Fe(por)(NO(3))] - Variable Coordination of Nitrate.

We report the X-ray crystal structures of two different iron(III) porphyrinates: [Fe(OEP)(NO(3))] and [Fe(TPP)(NO(3))]. The first complex has the nitrate ion coordinated by a single oxygen atom while the second derivative has the nitrate coordinated in a symmetric bidentate fashion. This latter structure is a redetermination that shows some differences from an earlier structure; the difference appears to be the result of an unrecognized nitrate ion disorder in the earlier structure determination. Changes in physical properties of three species ([Fe(TPivP)(NO(3))], [Fe(OEP)(NO(3))], and [Fe(TPP)(NO(3))] as a function of coordination mode were examined by Mössbauer and EPR spectroscopies; EPR spectra appear to be most sensitive to the change in coordination mode.