Chemistry - Coordination Chemistry Question with Solution | TestHub

In octahedral complexes, $t_{2g}$ orbitals contain lower energy electrons and $e_g$ orbitals contain higher energy electrons. We need the maximum $\frac{x}{y}$ (electrons in $t_{2g}$ / electrons in $e_g$).

(A) [FeF₆]³⁻: Fe³⁺ = d⁵ (high spin) → $t_{2g}{}^3{e}_g{}^2$, ratio = 3/2.

(B) [Ni(H₂O)₆]²⁺: Ni²⁺ = d⁸ → $t_{2g}{}^6{e}_g{}^2$, ratio = 6/2 = 3 (maximum).

(C) [Mn(H₂O)₆]²⁺:Mn²⁺ = d⁵ (high spin) → $t_{2g}{}^3{e}_g{}^2$, ratio = 3/2.

(D) [Co(H₂O)₃F₃]: Co²⁺ = d⁷ (high spin) → $t_{2g}{}^5{e}_g{}^2$, ratio = 5/2.

Answer: (B) [Ni(H₂O)₆]²⁺