Question

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

$I \, \left(\left[M n \left(H_{2} O\right)_{6}\right]\right)^{2 +}$

$II \, \left[M n \left(C N\right)_{2} \left(H_{2} O\right)_{4}\right]$

$III \,\left[ Mn ( CN )_{4}\left( H _{2} O \right)_{2}\right]^{2-}$

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

Answer 1

Answer: (A)

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