Question

For $M{n}^{3+}$, pairing energy is 28000 $c{m}^{-1}$. ${\Delta }_{o}for\left[Mn\right(CN{)}_6{]}^{3-}is38500c{m}^{-1}$. Which of the following is incorrect?

• A. Complex will be coloured
• B. Complex will be a low spin complex
• C. Net CFSE = -33600 $c{m}^{-1}$
• D. Complex will be colourless

Answer 1

The correct option is D Complex will be colourless

$\left[Mn\right(CN{)}_6{]}^{3-}$ has $t_{2g}^4,e_g^0$ due the presence of unpaired electrons, the complex will be coloured and it is a low spin complex.
$CFSE=-\frac{2}{5}{\Delta }_o{t}_{2g}+\frac{3}{5}{\Delta }_o{e}_g+P$
Since there is no electron in the $e_g$
$=-\frac{2}{5}38500\times 4+28000\times 1=33600c{m}^{-1}$
So the incorrect statement is option d