${\left[ {V\,{{\left( {CN} \right)}_6}} \right]^{4 - }}$ , ${\left[ {Fe\,{{\left( {CN} \right)}_6}} \right]^{4 - }}$ , ${\left[ {Ru\,{{\left( {N{H_3}} \right)}_6}} \right]^{3 + }}$ , અને ${\left[ {Cr\,{{\left( {N{H_3}} \right)}_6}} \right]^{2 + }}$
| Complex | Configuration | No. of unpaired electrons |
| $[V(CN)_6]^{4-}$ | $t_{2g}^3\,e_g^0$ | $3$ |
| ${[Cr{(N{H_3})_6}]^{2 + }}$ | $t_{2g}^4\,e_g^0$ | $2$ |
| ${[Ru{(N{H_3})_6}]^{3 + }}$ | $t_{2g}^5\,e_g^0$ | $1$ |
| ${[Fe{(CN)_6}]^{4 - }}$ | $t_{2g}^6\,e_g^0$ | $0$ |
Magnetic moment is directly proportion to number of unpaired electrons.
$(I)$ $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Br}_{2}$
$(II)$ $ \mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$
$(III)$ $\mathrm{Na}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]\left(\Delta_{0}>\mathrm{P}\right)$
$(IV)$ $\left(\mathrm{Et}_{4} \mathrm{N}\right)_{2}\left[\mathrm{CoCl}_{4}\right]$
$A: \left[ Ni ( en )_{3}\right]^{2+}, B :\left[ Ni \left( NH _{3}\right)_{6}\right]^{2+}, C :\left[ Ni \left( H _{2} O \right)_{6}\right]^{2+}$
