Question

Which of the following pairs of complex ions has higher value of ${\Delta }_o$ and why ?

$\left[Fe\right(C_2{O}_4{)}_3{]}^{4-}and\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$

Answer 1

$△0=F{e}^{3+}<F{e}^{2+}$

${Fe}^{3+}\to d^5\to CFSe=(-3\times \frac{3}{5}+2\times \frac{3}{5})=0{Fe}^{2+}\to d^6\to {t2g}^4{eg}^2\to CFSe=(-4\times \frac{2}{5}+2\times \frac{3}{5})=(-\frac{2}{5})△0$