Question

The CFSE for octahedral $[CoC{l}_6{]}^{4-}$ is $18,000c{m}^{–1}$.
The CFSE for tetrahedral $[CoC{l}_4{]}^{2-}$ will be

• A. $18,000c{m}^{–1}$
• B. $16,000c{m}^{–1}$
• C. $8,000c{m}^{–1}$
• D. $20,000c{m}^{–1}$

Answer 1

The correct option is C $8,000c{m}^{–1}$

The crystal field splitting in the tetrahedral field is intrinsically smaller than in the octahedral field. For most purposes the relationship may be represented as ${\Delta }_t=\frac{4}{9}{\Delta }_o$
${\Delta }_t=\frac{4}{9}\left(18000c{m}^{-1}\right)=8000c{m}^{-1}$