Question

Using MOT, compare $O_2^+$ and $O_2^-$ species and choose the incorrect option.

• A. $O _2^+$ have higher bond order than $O_2^-$ .
• B. $O _2^-$ is less stable
• C. $O _2^+$ is diamagnetic while $O _2^-$ is paramagnetic
• D. Both $O _2^+$ and $O _2^-$ are paramagnetic.

Answer 1

Answer: (C)

$O _2^{+}$and $O _2^{-}$both are paramagnetic as $O _2^{-}$has 1-unpaired electrons and $O _2^{+}$has one unpaired electron. Thus can be illustrated by MOT as
$O _2^{-} \rightarrow \sigma 1 s ^2 \sigma^* 1 s ^2 \sigma 2 s ^2 \sigma^* 2 s ^2 \sigma 2 p _{ z }^2 \pi 2 p _{ x }^2 \pi 2 p _{ y }^2 \pi^* 2 p _{ x }^2 \pi^* 2 p _{ y }^1 $
$O _2^{-} \Rightarrow B \cdot O =3 / 2 $
$O _2^{+} \rightarrow \sigma 1 s ^2 \sigma^* 1 s ^2 \sigma 2 s ^2 \sigma^* 2 s ^2 \sigma 2 p _{ z }^2 \pi 2 p _{ x }^2 \pi 2 p _{ y }^2 \pi^* 2 p _{ x }^1 \pi^* 2 p _{ y }^0 $
$O _2^{+} \Rightarrow B . O =5 / 2$ $ Higher the B.O. higher is the stability.