NO2 and CO have odd electron configration. But NO2 Dimerise but CO does not  ? 

Asked by Gishin Rajan | 11th Jan, 2016, 08:29: PM

Expert Answer:

In the NO2 molecule the nitrogen atom has a single unpaired electron. The molecule will tend to dimerise so that this unpaired electron can be paired with another to form stable N2O4 molecule
But CO is more reactive as compared to NO2. Also, it doesnot have unpaired electrons. Dimerisation takes place if there is some gain in bonding. But in the dimerization of CO, there is no gain of electrons because the bond order remains the same in the dimer. Hence, the dimer is unstable relative to the monomer in case of NO2

Answered by Hanisha Vyas | 12th Jan, 2016, 07:16: PM