What is the correct electronic configuration of the central atom in K4[Fe(CN)6] based on crystal field theory?
- t2g4 eg2
- t2g6 eg0
- e3 t23
- e4 t22
Answer
(2) t2g6 eg0
Solution
In K4[Fe(CN)6]: x + 6(−1) = −4 x = +2, so the central ion is Fe2+ (3d6).
The complex is octahedral, so the d orbitals split into t2g and eg sets (e and t2 are the tetrahedral sets).
As per NCERT, CN- is a strong field ligand ( o > P), so the electrons pair up in the t2g level:
configuration = t2g6 eg0 (low spin, diamagnetic)
Answer: (2)