The activation energies for these reactions are compared to find out the best carbene for N 2 activation. The orbital energies of carbenes and N 2 are analyzed to track down the electronic mechanism of nitrogen activation by carbene. How the substitutions at the nitrogen atom of the carbene frame affect the activation of the reaction is analyzed. On this basis carbene 5 R is modeled and continued for further investigation. The N 2 activation by carbene 5 R is found very good and better than all other carbenes considered earlier. Unfortunately, the Gibbs' free energy change for carbene 5 R -N 2 reaction is positive. Therefore, we extended our studies in two different avenues. First, we follow the use of persistent carbene to obtain a stable and thermodynamically favorable azo derivative. This technique is pursued due to the fact that the use of two carbenes for sequestering and conversation of SO 2 to valuable chemicals was proved effective. In the inquisition of efficient carbenes for N 2 activation, we also followed the substitution of the heteroatom of the carbene backbone. This methodology is accomplished owing to verifying the effect of substitution of the heteroatom nitrogen by phosphorus.