The second group form the bonds of considerably smaller fragilities (ca. by a factor 1/5), but still indicating explicit participation in the electron exchange in the reaction: C2-N1 and C2-O3 (Fig. ). Interesting information can be clearly deduced from Fig. : breaking the H4-N1 bond (Fig. ) is associated with increase of the C2-N1 bond order for a moment, while O3-C2 bond suffers a parallel decrease (Fig. ). It is rather unexpected that the H4-C2