Chemistry - Coordination Chemistry Question with Solution | TestHub

The C-O bond order in metal carbonyls is inversely related to the extent of metal-to-ligand $\pi$-backbonding. Greater electron density on the metal favors more backbonding, weakening the C-O bond and lowering its bond order. ${\left[\mathrm{V}(\mathrm{CO}{)}_6\right]}^{-}$ has the highest negative charge, leading to the most backbonding and thus the lowest C-O bond order.