Question

Which of the following carbonyls will have the strongest $C-O$ bond?

• A. $Mn{\left(CO\right)}_6^{+}$
• B. $Cr{\left(CO\right)}_6$
• C. $V{\left(CO\right)}_6^{-}$
• D. $Fe{\left(CO\right)}_5$

Answer 1

The correct option is A $Mn{\left(CO\right)}_6^{+}$

As the positive charge on the central metal atom increases, the less readily the metal can donate electron density into the ${\pi }^{\ast }$ orbitals of $CO$ ligand to weaken the $C-O$ bond. Due to this, the strength of the C-O bond increases.

The charge on the central metal atom is highest in $Mn{\left(CO\right)}_6^{+}$.

Hence the $C-O$ bond would be strongest in $Mn{\left(CO\right)}_6^{+}$.

Thus $Mn{\left(CO\right)}_6^{+}$ will have the strongest $C-O$ bond.

Therefore, the correct option is A.