The correct order of M-C π bond and strength in given metal carbonyls is

Question

The correct order of M-C π bond and strength in given metal carbonyls is (A) [ Fe ( CO )4]2->[ Co ( CO )4]->[ Ni ( CO )4] (B) [ Ni ( CO )4]>[ Co ( CO )4]->[ Fe ( CO )4]2- (C) [ Fe ( CO )4]2->[ Ni ( CO 4)]>[ Co ( CO )4]- (D) [ Ni ( CO )4]>[ Co ( CO )4]-=[ Fe ( CO )4]2-

Tardigrade Admin · Accepted Answer

The greater the positive charge on the central metal atom, less readily the metal can donate electron density into the π order of the carbon dioxide ligands to weaken the C-O bonds. Hence, more the -ve charge density on metal, more the strength of M-C π-bond.

Q. The correct order of $M - C π$ bond and strength in given metal carbonyls is

$[F e (CO)_{4}]^{2 -} > [C o (CO)_{4}]^{-} > [N i (CO)_{4}]$

$[N i (CO)_{4}] > [C o (CO)_{4}]^{-} > [F e (CO)_{4}]^{2 -}$

$[F e (CO)_{4}]^{2 -} > [N i (C O_{4})] > [C o (CO)_{4}]^{-}$

$[N i (CO)_{4}] > [C o (CO)_{4}]^{-} = [F e (CO)_{4}]^{2 -}$

The greater the positive charge on the central metal atom, less readily the metal can donate electron density into the $π$ order of the carbon dioxide ligands to weaken the $C - O$ bonds. Hence, more the $- v e$ charge density on metal, more the strength of $M - C π$ -bond.

Q. The correct order of M−Cπ bond and strength in given metal carbonyls is

[Fe(CO)4​]2−>[Co(CO)4​]−>[Ni(CO)4​]

[Ni(CO)4​]>[Co(CO)4​]−>[Fe(CO)4​]2−

[Fe(CO)4​]2−>[Ni(CO4​)]>[Co(CO)4​]−

[Ni(CO)4​]>[Co(CO)4​]−=[Fe(CO)4​]2−