The contour lines of the - 2 r superimposed on the molecular graphs for TS1-2x and TS1-3x for x= b, d and h are shown in Figure (the plots for the remaining TSs are shown in the Supporting Information). The electron density distribution on the C 1 -N 1 and C 3 -N 3 interactions in the TS1-2x graphs are indicative of closed shell interactions. As a result of the breaking of the C 1 -N 1 bond, there is a region of electron charge depletion on the outermost shell of C 1 (indicated with an arrow), which is more notable for TS1-2b and TS1-2d than for the TS1-2h.