Electron occupany for octahedral complexes of d4 metals or metal ions
If the ligand is
- weak, each orbital must be singly occupied before any pairing
- strong, electrons pair in the t2g before any electrons occupy the eg orbitals
eg 
t2g weak field ligand
high spin d4 complex
| eg | | |
| t2g |  | |
| strong field ligand low spin d4complex | ||