Q

# How would you account for the following: Of the d^4 species Cr^2+ is strongly reducing while manganese (III) is strongly oxidising.

8.21 How would you account for the following:

(i) Of the $d^{4}$ species, $Cr^{2+}$ is strongly reducing while manganese(III) is strongly oxidising.

$Cr^{2+}$is strongly reducing in nature. It has $d^{4}$ configuration. By losing one electron it gets oxidised to $Cr^{3+}$(electronic configuration $d^{3}$) which can be written as $t^{3}_{2g}$ and it is a more stable configuration. On the other hand $Mn^{3+}$ has also $d^{4}$ configuration by accepting one electron it gets reduced and act as strongly oxidising agent(electronic configuration $d^{5}$). Thus it is extra stable due to half -filled with d-orbital.