To validate the proposed electronic mechanism of the carbene-N 2 reaction depicted above, the change in the HOMO electron cloud of the diazo derivative formation along the reaction path is captured and construed in Figure . Single-point energy calculation is carried out for selected geometries obtained from the IRC study. Since electronic wave functions are optimized independently at a particular geometry, the pictures of electron distribution of HOMOs at different geometries collectively mimic the snapshots of the flow of electrons The overlap is almost completed at IG10 which is very close to the product. From these observations, it may be concluded that this reaction occurs through the σ electron donation of nitrogen and back donation of carbene. However, there is a significant time gap between the completion of bonding and the beginning of the back-bonding. We may consider this state as the rest phase of the reaction where no orbital electron movement is observed. For this reaction, the rest phase is observed at the transition state itself.