Chemistry - Coordination Chemistry Question with Solution | TestHub

The compound is Hg[Co(SCN)₄].

First, determine the oxidation state of Co. Since Hg is +2, the complex ion [Co(SCN)₄] must be -2. As SCN⁻ is -1, Co must be in the +2 oxidation state.

Co²⁺ has a d⁷ configuration. SCN⁻ is a weak field ligand, so it forms a high-spin tetrahedral complex.

The electron configuration for high-spin Co²⁺ (d⁷) in a tetrahedral field is $t_2^4{e}^3$.

Number of unpaired electrons (n) = 3.

Spin-only magnetic moment $\mu =\sqrt{n(n+2)}$ BM.

$\mu =\sqrt{3(3+2)}=\sqrt{3\times 5}=\sqrt{15}$ BM.