Question

The crystal field splitting energy (CFSE) for $\left[C o C l_{6}\right]^{4 -}$ is about 18000 $cm^{- 1}$ . What would be the CFSE value for $\left[\right.CoCl_{4}\left]\right.^{2 -}$ ?

Answer 1

$\operatorname{CFSE}\left(\Delta_0\right)$ of $\left[\mathrm{CoCl}_6\right]^{4-}=18000 \mathrm{~cm}^{-1}$

$\operatorname{CFSE}\left(\Delta_{\mathrm{t}}\right)$ of $\left[\mathrm{CoCl}_4\right]^{2-}=$ ?

From formula, $\Delta _{t}=\frac{4}{9}\times \Delta _{0}$

$=\frac{4}{9}\times 18000 \, cm^{- 1}$

$=8000 \, cm^{- 1}$