Which of the following carbonyls will have the strongest $\mathrm{C}-\mathrm{O}$ bond ?
Which of the following carbonyls will have the strongest $\mathrm{C}-\mathrm{O}$ bond ?
$\left[\mathrm{Mn}(\mathrm{CO})_{6}ight]^{+}$
$\left[\mathrm{Cr}(\mathrm{CO})_{6}ight]$
$\left[\mathrm{V}(\mathrm{CO})_{6}ight]^{-}$
$\left[\mathrm{Fe}(\mathrm{CO})_{5}ight]$
Solution
As positive charge on the central metal atom increases, the less readily the metal can donate electron density into the $\pi^{*}$ orbitals of CO ligand (donation of electron density into $\pi^{*}$ orbitals of $\mathrm{CO}$ result in weakening of $\mathrm{C}-\mathrm{O}$ bond ). Hence, the $\mathrm{C}-\mathrm{O}$ bond would be strongest in $\left[\mathrm{Mn}(\mathrm{CO})_{6}ight]^{+}$
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