Question

Which of the following statements is incorrect for CO molecules?
(a) Intramolecular Lewis acid-base interaction is present
(b) Charge separation is present
(c) $$\sigma$$-bonds, $$\pi$$-bond and back-bonding all are present together
(d) Direction of dipole moment is from C to O.

Answer 1

Hint: Carbon monoxide or CO has a carbon and oxygen atom. The bond between the carbon and oxygen atom is unsaturated and is a triple bond.

Complete step-by-step answer:
Let us discuss each option given in the question.
-C in carbon monoxide is less electronegative than oxygen. C tends to accept electrons, that is it can act as a lewis acid, while oxygen can donate electrons, that it is a lewis base. Thus, in carbon monoxide there is intermolecular lewis acid-base interaction. So, option (a) is correct.

-There is a triple bond between carbon and oxygen in carbon monoxide. It also has three resonance structures as shown below in the figure. Out of the three resonance structures, two structures have charge separation. Thus the option (b) is also correct.
$$:\stackrel{-}{C}\equiv \stackrel{\oplus }{O}:\leftrightarrow :C=\stackrel{}{O}:\leftrightarrow :\stackrel{\oplus }{C}-\underset{..}{\stackrel{..}{O}}:$$

-We know carbon monoxide has a triple bond. So, its bond order is three. This shows that it has a sigma bond between carbon and oxygen, a pi bond and also the third bond is due to back bonding. Thus, option (c) is also correct.

-The electronegativity of carbon is less than that of oxygen. So, the dipole moment is from oxygen to carbon and not from carbon to oxygen. Thus, the last option is incorrect.
Therefore, the last option (d) is incorrect- Direction of dipole moment is from C to O.

Note: The triple bond in carbon monoxide is due to the back bonding in it. The electrons from carbon are donated to the empty orbital of oxygen.