Question

What is the correct electronic configuration of the central atom in K₄[Fe(CN)₆] based on crystal field theory?

पर्याय

• \[\ce{t^4_{2g}e^2_{g}}\]

• \[\ce{t^6_{2g}e^0_{g}}\]

• \[\ce{e^3 t^3_{2}}\]

• \[\ce{e^4 t^2_{2}}\]

Answer 1

\[\ce{t^6_{2g}e^0_{g}}\]

Explanation:

In K₄[Fe(CN)₆], the central metal is Fe²⁺

• Fe has an atomic number of 26, so its electron configuration is [Ar] 3d⁶ 4s².
• For Fe²⁺, two electrons are removed, typically from the 4s orbital, giving it the configuration [Ar] 3d⁶.

Since CN⁻ is a strong field ligand, it causes large d-orbital splitting in the octahedral field. For Fe²⁺ (3d⁶), the complex adopts a low-spin configuration, where all 6 electrons are placed in the lower-energy t_2g​ orbitals, and none are placed in the higher-energy e_g​ orbitals.

Final electronic configuration for Fe²⁺ in K₄[Fe(CN)₆]:

Fe²⁺: \[\ce{(t^6_{2g}) (e^0_{g})}\]