Question

Value of CFSE, in tetrahedral complex having $3d^4$ configuration of metal ion, surrounded by weak field ligands, will be

• A. $+\frac{2}{5}{\Delta }_t$
• B. $+\frac{3}{5}{\Delta }_t$
• C. $-\frac{2}{5}{\Delta }_t$
• D. $-\frac{4}{5}{\Delta }_t$

Answer 1

The correct option is C $-\frac{2}{5}{\Delta }_t$

CFSE for tetrahedral complex is given as
$=[\frac{-3}{5}{e}_g+\frac{2}{5}{t}_{2g}]{\Delta }_t$
where ${\Delta }_t=\frac{4}{9}{\Delta }_0$
$3d^4$ configuration in weak field ligand is $e_g^2{t}_{2g}^2$

$=[\frac{-3}{5}\times 2+\frac{2}{5}\times 2]{\Delta }_t$
$=\frac{-2}{5}{\Delta }_t$
Hence option (a) is correct.