The first set of systems having C-Ng-N bonding unit is predicted herein through the analysis of stability and bonding in NCNgNSi (Ng = Kr-Rn) family. They are thermochemically stable with respect to all dissociation channels, but for the one producing CNSiN and free Ng. Ng is bound with the adjacent atoms through a delocalized 3c–3e σ-bond involving a C-Ng-N moiety and a totally delocalized 5c-2e σ-bond in these compounds, which represents an unprecedented bonding nature, as in Ng-inserted compounds Ng usually forms one covalent and one ionic bond with the neighboring elements. For more information, see the Full Paper by S. Pan et al. on page 2879 ff.