CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

Among the following metal carbonyls, the $$C-O$$ bond order is lowest in


A
[Mn(CO)6]+
loader
B
[Fe(CO)5]
loader
C
[Cr(CO)6]
loader
D
[V(CO)6]
loader

Solution

The correct option is D $$[V(CO)_6]^-$$
The overlap of a lone pair on the C atom with the empty hybrid metal orbital forms a metal-to-carbon $$\sigma$$-bond. The transition metal atom in a metal carbonyl fills the non-bonding d-orbitals which are proper symmetry to overlap with the anti-bonding orbitals of CO. The electronic charge is transferred from the filled non-bonding orbitals of the metals to $$\pi^{\star}$$-orbitals of the ligand CO. This reduces the bond order of CO. The $$\pi$$ back-bonding strengthens the M-C bond order and weakens the C-O bond order.
CO is a strong ligand, it causes pairing of electrons.
$$Mn^+:(z=25)$$
$$[Ar]3d^54s^1\Rightarrow [Ar]3d^64s^0$$
Three lone pairs are available for back-bonding with vacant orbital of C in CO.
$$Fe^0:(z=26)$$
$$[Ar]3d^64s^2\Rightarrow [Ar]3d^8$$
Four lone pairs are available for back-bonding with vacant orbotal of C in CO.
$$Cr^0:(z=24)$$
$$[Ar]3d^54s^1\Rightarrow [Ar]3d^64s^0$$
Three loan pairs are available for back-bonding with vacant orbital of C in CO.
$$V^-:(z=23)$$
$$[Ar]3d^44s^2\Rightarrow [Ar]3d^64s^0$$
Three lone pairs are available for back-bonding with vacant orbital of C in CO.
Minimum back-bonding is possible in $$[V(CO)_6]^{-1}$$, so the M-C bond order is the lowest.

Chemistry

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image