-
$\text{Co}^{2+}=3\text{d}^7$
Number of unpaired electrons = 4
Magnetic moment
$=\sqrt{\text{n}(\text{n}+2)}=\sqrt{4(4+2)}=4.9\text{B.M.}$
$[\text{Co(H}_2\text{O})_6]^{2+}:$
$\text{Co}^{2+}=3\text{d}^7$
Number of unpaired electrons = 3
Magnetic moment = $\sqrt{3(3+2)}=3.87\text{B.M.}$
$[\text{Co(CN)}_6]^{3-}:$
$\text{Co}^{3+}=3\text{d}^6$
Number of unpaired electrons = 0
Diamagnetic.
- $\text{FeF}^{3-}_6:$
$\text{Fe}^{3+}=3\text{d}^5$
Number of unpaired electrons = 5
Magnetic moment = $\sqrt{5(5+2})=5.92\text{B.M.}$
$[\text{Fe(H}_2\text{O})_6]^{2+}:$
$\text{Fe}^{2+}=3\text{d}^6$
Number of unpaired electrons = 4
Magnetic moment = $\sqrt{4(4+2})=4.9\text{B.M.}$
$[\text{Fe(CN)}_6]^{4-}:$
$\text{Fe}^{2+}=3\text{d}^6$
Diamagnetic.