Question

Predict the order of ${\Delta }_{{}^{\circ }}$ for the following compounds

$I{\left(\left[Mn{\left(H_{2}O\right)}_6\right]\right)}^{2+}$

$II\left[Mn{\left(CN\right)}_2{\left(H_{2}O\right)}_4\right]$

$III{\left[Mn(CN{)}_4{\left(H_{2}O\right)}_2\right]}^{2-}$

• A. ${\left(\Delta \right)}_{{}^{\circ }}\left(I\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(II\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(III\right)$
• B. ${\left(\Delta \right)}_{{}^{\circ }}\left(II\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(I\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(III\right)$
• C. ${\left(\Delta \right)}_{{}^{\circ }}\left(III\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(II\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(I\right)$
• D. ${\left(\Delta \right)}_{{}^{\circ }}\left(I\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(III\right)<{\left(\Delta \right)}_{{}^{\circ }}\left(II\right)$

Answer 1

Answer: (A)

$C{N}^{-}$ is a strong field ligand so greater the number of $C{N}^{-}$ , more will be the strength of ligands and more will be the value of ${\Delta }_o$ (crystal field splitting energy).