Question

Choose the correct statement with respect to the bond length of $CO$ and $CO^{+}$ :

• A. The bond length in $CO$ is $1.128 \, \mathring{A}$ and $C O^{+}$ is $1.115 \, \mathring{A}$ because during conversion of $CO$ to $C O^{+}$ , electron is removed from anti bonding orbital.
• B. The bond length in $CO$ is $1.115 \, \mathring{A}$ and $C O^{+}$ is $1.128 \, \mathring{A}$ because during conversion of $CO$ to $CO^{+}$ electron is removed from bonding orbital.
• C. During conversion of $CO$ to $C O^{+}$ bond length does not vary because bond order remain same.
• D. The bond length in $CO$ is $1.115 \, \mathring{A}$ and $C O^{+}$ is $1.128 \, \mathring{A}$ because bond order decreases during conversion of $CO$ to $C O^{+}$ .

Answer 1

Answer: (A)

Because of the greater difference in electronegativity between $C$ and $O$, the energy of the molecular orbitals in CO are in the following order,
$\sigma_{1 s }^2 \sigma_{1 s }^{* 2} \sigma_{2 s }^2 \pi_{2 p _{ y }}^2=\pi_{2 p _{ z }}^2 \sigma_{2 p _{ z }}^2 \sigma_{2 s }^{* 2}$
Bond order in $CO =\frac{1}{2} 10-4=3$
When $CO$ is converted to $CO ^{+}$, one electron is removed from antibonding molecular orbitals. Hence, the bond order in $CO ^{+}$is greater than $CO$.