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 $\left[ CoCl _{6}\right]^{4-}=18000 cm ^{-1}$
$\operatorname{CFSE}\left(\Delta_{ t }\right)$ of $\left[ CoCl _{4}\right]^{2-}=?$
From formula, $\Delta _{t}=\frac{4}{9}\times \Delta _{0}$
$=\frac{4}{9}\times 18000 \, cm^{- 1}$
$=8000 \, cm^{- 1}$