Question

Amongst the following ions which one has the highest magnetic moment value?
[At. no. $Co = 27$ ,$Ni = 28$]
A .${\left[ {Co{{(N{H_3})}_6}} \right]^{3 + }}$
B. ${\left[ {Co{F_6}} \right]^{3 - }}$
C.${\left[ {NiC{l_4}} \right]^{2 - }}$
D. ${\left[ {Ni{{(CN)}_4}} \right]^{2 - }}$
E. $\left[ {Ni{{(CO)}_4}} \right]$

Answer 1

Hint:A compound containing coordinate bonds, typically between a central metal atom and a number of other atoms or groups is known as coordination compound. Coordination compounds play a vital role in metallurgy and biological systems as well as in analytical chemistry also.

 Complete step by step answer:
As we all know that the magnetic moment depends on the number of unpaired electrons.
So we will calculate the number of unpaired electrons of each complex and then find its magnetic moment and our last step will be comparison of all the magnetic moments.
${\left[ {Co{{(N{H_3})}_6}} \right]^{3 + }}$ has $Co$ as its central atom which is in $ + 3$ oxidation state. So it has zero unpaired electrons.
Magnetic moment, $\mu = \sqrt {n(n + 2)} $ ($n = $ number of unpaired electrons)
So, $\mu = 0$
${\left[ {Co{F_6}} \right]^{3 - }}$ has $Co$ as its central atom which is in $ + 3$ oxidation state. So it has four unpaired electrons.
Magnetic moment, $\mu = \sqrt {n(n + 2)} $ ($n = $ number of unpaired electrons)
So, $\mu = \sqrt {4(4 + 2)} = \sqrt {24} = 4.89$
${\left[ {NiC{l_4}} \right]^{2 - }}$ has $Ni$ as its central atom which is in $ + 2$ oxidation state. So it has two unpaired electrons.
Magnetic moment, $\mu = \sqrt {n(n + 2)} $ ($n = $ number of unpaired electrons)
So, $\mu = \sqrt {2(2 + 2)} = \sqrt 8 = 2.82$
${\left[ {Ni{{(CN)}_4}} \right]^{2 - }}$ has $Ni$ as its central atom which is in $ + 2$ oxidation state. So it has zero unpaired electrons.
Magnetic moment, $\mu = \sqrt {n(n + 2)} $ ($n = $ number of unpaired electrons)
So, $\mu = 0$.
$\left[ {Ni{{(CO)}_4}} \right]$ has $Ni$ as its central atom which is in $0$ oxidation state. So it has zero unpaired electrons.
Magnetic moment, $\mu = \sqrt {n(n + 2)} $ ($n = $ number of unpaired electrons)
So, $\mu = 0$.
So we can see that ${\left[ {Co{F_6}} \right]^{3 - }} $ has the highest magnetic moment.

So, option (B) is correct.

Note:
The magnetic moment $(\mu )$ basically is the property of the magnet that interacts with an applied field to give a mechanical movement. Hence we have checked the magnetic properties of the given compounds in this problem.