What can be inferred from the magnetic moment values of the following complex species?
Example | Magnetic Moment $(BM)$ |
$K _{4}\left[ Mn ( CN )_{6}\right.$ | $2.2$ |
$\left[ Fe \left( H _{2} O \right)_{6}\right]^{2+}$ | $5.3$ |
$K _{2}\left[ MnCl _{4}\right]$ | $5.9$ |
Magnetic moment $\left( \mu \right)$ is given as $\mu=\sqrt{n(n+2)}$
For value $n=1,$ $\mu=\sqrt{1(1+2)}=\sqrt{3}=1.732$
For value $n=2,$ $\mu=\sqrt{2(2+2)}=\sqrt{8}=2.83$
For value $n=3,$ $\mu=\sqrt{3(3+2)}=\sqrt{15}=3.87$
For value $n=4,$ $\mu=\sqrt{4(4+2)}=\sqrt{24}=4.899$
For value $n=5,$ $\mu=\sqrt{5(5+2)}=\sqrt{35}=5.92$
$(i)$ $K _{4}\left[ Mn ( CN )_{6}\right]$
For in transition metals, the magnetic moment is calculated from the spin-only formula. Therefore,
$\sqrt{n(n+2)}=2.2$
We can see from the above calculation that the given value is closest to $n=1$. Also, in this complex, Mn is in the $+2$ oxidation state. This means that $Mn$ has $5$ electrons in the $d$ orbital.
Hence, we can say that $CN ^{-}$ is a strong field ligand that causes the pairing of electrons.
$(ii)$ $\left[ Fe \left( H _{2} O \right)_{6}\right]^{2+}$
$\sqrt{n(n+2)}=5.3$
We can see from the above calculation that the given value is closest to $n=4$. Also, in this complex, $Fe$ is in the $+2$ oxidation state. This means that $Fe$ has $6$ electrons in the $d$ -orbital
Hence, we can say that $H _{2} O$ is a weak field ligand and does not cause the pairing of electrons.
$(iii)$ $K _{2}\left[ MnCl _{4}\right]$
$\sqrt{n(n+2)}=5.9$
We can see from the above calculation that the given value is closest to $n=5$. Also, in this complex, $M n$ is in the $+2$ oxidation state. This means that $M n$ has $5$ electrons in the $d$ -orbital.
Hence, we can say that $Cl ^{-}$ is a weak field ligand and does not cause the pairing of electrons.
Which of the following pairs of elements cannot form an alloy
The correct order of decreasing third ionisation enthalpy of $Ti,\, V,\, Cr,\, Mn$ is
Why first ionisation enthalpy of $Cr$ is lower than that of $Zn$ ?
The number of $d-$ electrons in $F{e^{2 + }}$ (at no. of $Fe = 26$) is not equal to that of the