Question

The CFSE for $\left[\right.CoCl_{6}\left]\right.^{4 -}$ complex is 18000 $cm^{- 1}$ . The $\Delta $ for $\left[\right.CoCl_{4}\left]\right.^{2 -}$ will be

• A. $9000\text{ c}\text{m}^{- 1}$
• B. $4000\text{ c}\text{m}^{- 1}$
• C. $8000\text{ c}\text{m}^{- 1}$
• D. $2000\text{ c}\text{m}^{- 1}$

Answer 1

Answer: (C)

The relation of CFSE for tetrahedral and octahedral complex is given as

$\Delta _{t}=\frac{4}{9}\Delta _{0}$

So $\Delta _{t}$ for $\left[\right.CoCl_{4}\left]\right.^{2 -}=\frac{4}{9}\times 18000\text{c}\text{m}^{- 1}$

$=8000\text{ c}\text{m}^{- 1}$ .