Table 1.
Partial occupancies (spin densities, i.e. α-β differences) for the iron dxz and dyz orbitals in models of the nitrite adducts of cytochrome cd1 nitrite reductase (at previously reported geometry and after rotation of the nitrite ligand by 45°, respectively) and of globins (‘Mb’ – freely optimized, ‘45°’ – nitrite ligand rotated around the Fe-N bond by 45°; ‘Mb OH− – nitrite replaced with hydroxide; Mb CN− – nitrite replaced by cyanide. Data from UBP86/6-31G** geometry optimizations followed by Mulliken population analyses.
| dxz | dyz | dxz/dyz | |
|---|---|---|---|
| cd1 NO2− | 0.39 | 0.32 | 1.2 |
| cd1 NO2− 45° | 0.78 | 0.08 | 9.8 |
| Mb NO2− | 0.63 | 0.18 | 3.5 |
| Mb OH− | 0.63 | 0.08 | 7.9 |
| Mb CN− | 1.08 | 0.08 | 13.5 |
| Mb NO2− 45° | 0.47 | 0.35 | 1.3 |