The $d - $electronic configuration of ${\rm{C}}{{\rm{r}}^{2 + }},{\rm{\;M}}{{\rm{n}}^{2 + }},{\rm{F}}{{\rm{e}}^{2 + }},{\rm{N}}{{\rm{i}}^{2 + }}{\rm{\;are\;}}3{{\rm{d}}^4},3{{\rm{d}}^5},3{{\rm{d}}^6}{\rm{\;and\;}}3{{\rm{d}}^8}$ respectively. Which of the following complex will show minimum paramagnetic behaviour?

${\left[ {{\rm{Ni}}{{\left( {{{\rm{H}}_2}{\rm{O}}} \right)}_6}} \right]^{2 + }}$

${\left[ {{\rm{Fe}}{{\left( {{{\rm{H}}_2}{\rm{O}}} \right)}_6}} \right]^{2 + }}$

${\left[ {{\rm{Cr}}{{\left( {{{\rm{H}}_2}{\rm{O}}} \right)}_6}} \right]^{2 + }}$

${\left[ {{\rm{Mn}}{{\left( {{{\rm{H}}_2}{\rm{O}}} \right)}_6}} \right]^{2 + }}$

NEET UG CHEMISTRY MCQ: CO-ORDINATION COMPOUNDS

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The

d -

electronic configuration of

\mathrm{C}{\mathrm{r}^{2 + }},\mathrm{\;M}{\mathrm{n}^{2 + }},\mathrm{F}{\mathrm{e}^{2 + }},\mathrm{N}{\mathrm{i}^{2 + }}\mathrm{\;are\;}3{\mathrm{d}^4},3{\mathrm{d}^5},3{\mathrm{d}^6}\mathrm{\;and\;}3{\mathrm{d}^8}

respectively. Which of the following complex will show minimum paramagnetic behaviour?

View answer and explanation

Correct option: B

{\left[ {\mathrm{Ni}{{\left( {{\mathrm{H}_2}\mathrm{O}} \right)}_6}} \right]^{2 + }}

Option B is correct.

{\left[ {\mathrm{Ni}{{\left( {{\mathrm{H}_2}\mathrm{O}} \right)}_6}} \right]^{2 + }}

has the minimum paramagnetic behavior because it has the least number of unpaired electrons among the given options.