Question

Of the two ions ${\left[Fe{\left(CN\right)}_6\right]}^{-3}$ and ${\left[Fe{\left(CN\right)}_6\right]}^{-4}$ , the diamagnetic ion is ____.

• A. ${\left[Fe{\left(CN\right)}_6\right]}^{-3}$
• B. ${\left[Fe{\left(CN\right)}_6\right]}^{-4}$
• C. both of these
• D. none of these

Answer 1

Answer: (B)

${\left[Fe{\left(CN\right)}_6\right]}^{-4}$

In $\left[Fe\right(CN{)}_6{]}^{-3}$, $Fe$ is in $+3$ state.

$x+6(-1)=-3$

$x=+3$

In $\left[Fe\right(CN{)}_6{]}^{-4}$, $Fe$ is in $+2$ state.

Orbitals of $F{e}^{2+}$ is

$\uparrow \uparrow \uparrow \uparrow$

$3d$ $4s$ $4p$ $4d$

Orbitals in $\left[Fe\right(CN{)}_6{]}^{-4}$ is:

$\upharpoonleft \upharpoonright \upharpoonleft \upharpoonright$

$d^{2}s{p}^2$

Orbitals in $F{e}^{+3}$ is:

$\uparrow \uparrow \uparrow$

$3d$ $4s$ $4p$

Orbitals in $\left[Fe\right(CN{)}_6{]}^{-3}$ is:

$\upharpoonleft \upharpoonright \upharpoonleft$

$d^{2}s{p}^2$

In $\left[Fe\right(CN{)}_6{]}^{-4}$, there is no lone pair. So it is a diamagnetic ion.