Question

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

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

Answer 1

Answer: (A)

$e^{-}$density in metal ion $\propto$ synergic bond $\propto C-O$ $BL\propto \frac{1}{C-O}$ bond strength.