Table 3. Haem iron-coordination geometry.
The values in parentheses represent the estimated standard deviations derived from least-squares refinement using SHELXL.
| Oxidized form 1 | Oxidized form 2 | Reduced form 1 | Reduced form 2 | |Oxidized reduced| form 1 | |Oxidized reduced| form 2 | Oxidized |form 1 form 2| | Reduced |form 1 form 2| | |
|---|---|---|---|---|---|---|---|---|
| Distances () | ||||||||
| FeHis44N2 | 2.004 (4) | 1.996 (9) | 2.013 (3) | 1.984 (11) | 0.009 | 0.012 | 0.008 | 0.029 |
| FeHis68N2 | 1.992 (5) | 1.975 (8) | 2.022 (4) | 1.970 (9) | 0.030 | 0.005 | 0.017 | 0.052 |
| FeNI | 1.996 (6) | 2.008 (8) | 2.012 (4) | 2.020 (9) | 0.016 | 0.012 | 0.012 | 0.008 |
| FeNII | 1.986 (5) | 1.997 (7) | 2.003 (3) | 1.997 (8) | 0.017 | 0.000 | 0.011 | 0.006 |
| FeNIII | 1.979 (6) | 1.961 (8) | 1.999 (4) | 1.955 (9) | 0.020 | 0.006 | 0.018 | 0.044 |
| FeNIV | 2.004 (5) | 1.998 (7) | 1.997 (3) | 1.995 (8) | 0.007 | 0.003 | 0.006 | 0.002 |
| Angles () | ||||||||
| His44 N2FeHis68 N2 | 177.9 (2) | 177.9 (3) | 178.6 (1) | 177.7 (4) | 0.7 | 0.2 | 0.0 | 0.9 |
| NIFeNIII | 179.2 (2) | 179.2 (3) | 179.3 (2) | 179.1 (4) | 0.1 | 0.1 | 0.0 | 0.2 |
| NIIFeNIV | 178.9 (2) | 179.1 (3) | 179.5 (1) | 178.3 (4) | 0.6 | 0.8 | 0.2 | 1.2 |
| His44 imidazole(NIINIV)† | 46.5 | 45.1 | 46.9 | 46.0 | 0.4 | 0.9 | 1.4 | 0.9 |
| His68 imidazole(NIINIV)† | 17.9 | 25.8 | 18.1 | 26.1 | 0.2 | 0.3 | 7.9 | 8.0 |
†
The angle of the His imidazole plane against the NIINIV axis on the haem plane. Positive and negative values represent the clockwise and counterclockwise directions to the NIINIV axis viewing from the axial ligands.