Question

Low spin complex of $d^6$ cation in an octahedral field will have how much energy?
(${\Delta }_0=$ crystal field splitting energy in an octahedral field,
P = electron pairing energy)

• A. $-\frac{12}{5}{\Delta }_0+P$
• B. $-\frac{12}{5}{\Delta }_0+3P$
• C. $-\frac{2}{5}{\Delta }_0+2P$
• D. $-\frac{2}{5}{\Delta }_0+P$

Answer 1

The correct option is B $-\frac{12}{5}{\Delta }_0+3P$

The electronic configuration of the $d^6$ low spin complex is $t_{2g}^6{e}_g^0$
So CFSE will be, $=(-0.4\times 6+0\times 0.6){\Delta }_0+3P$
$=-\frac{12}{5}{\Delta }_0+3P$