Chemistry - Coordination Chemistry Question with Solution | TestHub

Among the given option (a) is a diamagnetic complex.

(a) ${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6\right]}^{3+}\Rightarrow \mathrm{Co}\left(27\right)\Rightarrow {\mathrm{Co}}^{3+}=3{\mathrm{d}}^{6}4{\mathrm{s}}^0$.

Thus, has no unpaired electrons and is a diamagnetic complex.

(b) ${\left[{\mathrm{NiCl}}_4\right]}^{2-}\Rightarrow \mathrm{Ni}\left(28\right)\Rightarrow {\mathrm{Ni}}^{2+}=3{\mathrm{d}}^{8}4{\mathrm{s}}^0$ 

Thus, has two unpaired electrons is paramagnetic.

(c) ${\left[{\mathrm{CuCl}}_4\right]}^{2-}\Rightarrow \mathrm{Cu}\left(29\right)\Rightarrow {\mathrm{Cu}}^{2+}=3{\mathrm{d}}^{9}4{\mathrm{s}}^0$

Thus, has one unpaired electrons and is paramagnetic.

(d) ${\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{3+}\Rightarrow \mathrm{Fe}\left(26\right)\Rightarrow {\mathrm{Fe}}^{3+}=3{\mathrm{d}}^{5}4{\mathrm{s}}^0$

Thus, has five unpaired electrons and is paramagnetic.