In the complex , how many electrons occupy the triply degenerate orbitals of the central iron atom? — Coordination Compounds Chemistry Question

💡 Solution & Explanation

The complex is $K_4[Fe(CN)_6]$, meaning the coordination sphere is $[Fe(CN)_6]^{4-}$. The oxidation state of Iron is $+2$, yielding a $3d^6$ configuration. The cyanido ligand ($CN^-$) is a strong field ligand, so the splitting energy $\Delta_o > P$ (pairing energy). Thus, the electrons will completely pair up in the lower energy $t_{2g}$ orbitals before any occupy the $e_g$ orbitals. The configuration is $t_{2g}^6 e_g^0$. Therefore, there are $6$ electrons in the $t_{2g}$ orbitals.