| Complex | Oxidation State of Co | d-Electron Configuration | Geometry | Spin State | Hybridisation | Magnetic Nature |
|---|---|---|---|---|---|---|
| [Co(NH₃)₆]³⁺ | +3 | 3d⁶ | Octahedral | Low spin | d²sp³ | Diamagnetic |
| [Co(NH₃)₅Cl]²⁺ | +3 | 3d⁶ | Octahedral | Low spin | d²sp³ | Diamagnetic |
| [Co(NH₃)₄Cl₂]⁺ | +3 | 3d⁶ | Octahedral | Low spin | d²sp³ | Diamagnetic |
| [Co(NH₃)₆]²⁺ | +2 | 3d⁷ | Octahedral | High spin | sp³d² | Paramagnetic |
| [Co(NH₃)₅Cl]⁺ | +2 | 3d⁷ | Octahedral | High spin | sp³d² | Paramagnetic |
| [Co(NH₃)₄Cl₂] | +2 | 3d⁷ | Octahedral | High spin | sp³d² | Paramagnetic |
Important Notes
- Octahedral Co(III) complexes with NH₃ are generally low spin and diamagnetic.
- Octahedral Co(II) complexes with NH₃ are generally high spin and paramagnetic.
- Low-spin Co(III), d⁶: t₂g⁶ e_g⁰; zero unpaired electrons.
- High-spin Co(II), d⁷: t₂g⁵ e_g²; three unpaired electrons.
- The hybridisation assignments follow the traditional valence-bond theory model.
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