Table 4.
Summary of the Experimental EPR and Mossbauer Results for the Investigated High-Spin Ferrous Heme Complexes
| [Fe(TPP)(2-MeHIm)] | [Fe(TPP)(2-MeIm–)]– | [Fe(TpivPP)Cl]– | |
|---|---|---|---|
| D (cm–1) | +0.9a | –8b | n/ac |
| δ (mm/s) | 0.85 | 1.00 | 1.01 |
| ΔEq (mm/s) | –1.95 | +3.60 | 4.36 |
| η | 0.8 | 0.02 | n/ac |
a
D = –5.0 cm–1 had initially been obtained by Lang et al. (J. Chem. Phys. 1979, 71, 4899) from Mössbauer spectroscopy at 6T. This value was later corrected to a positive D of about 5–30 cm–1 based on variable-field Mössbauer measurements by Scheidt and coworkers (J. Am. Chem. Soc. 2005, 127, 5675). However, Mössbauer fits are not very sensitive to the value of D, and hence, the EPR-based value presented here is much more reliable.
b
Determined for [Fe(OEP)(2-MeIm–)]–.
c
Not available