Question

The number of unpaired electrons responsible for the paramagnetic nature of the following complex species are respectively :

\([Fe(CN)_6]^{3-} , [FeF_6]^{3-} , [CoF_6]^{3-}, [Mn(CN)_6]^{3-}\)

(1) 1, 5, 4, 2

(2) 1, 5, 5, 2

(3) 1, 1, 4, 2

(4) 1, 4, 4, 2

Answer 1

Correct option is: (1) 1, 5, 4, 2

\([Fe(CN)_6]^{3-} \Rightarrow Fe^{3+}, d^5, t_{2g} ^5, e_g ^0 \Rightarrow 1 \ \text{unpaired electron}\)

\([FeF_6]^{3-} \Rightarrow Fe^{3+}, d^5, t_{2g}^3 e_g ^2 \Rightarrow 5 \ \text{unpaired electrons}\)

\([CoF_6]^{3-} \Rightarrow Co^{3+}, d^6, t_{2g}^4 e_g ^2 \ \ \Rightarrow \ 4 \ \text{unpaired electrons}\)

\([Mn(CN)_6]^{3-} \Rightarrow Mn^{3+} , d^4, t_{2g}^4 e_g^0 \ \ \Rightarrow \ \ 2 \ \text{unpaired electrons}\)