Aromaticity in Planar Sulfur-Nitrogen Rings

This feature of the electronic structure of these inorganic rings is especially dramatic for the six-atom system [SsNs], which is able to accommodate ten r-electrons, cf. six r-electrons for CeHg. The electron-richness of [SsNs] results in a significantly lower r-bond order of 0.17 

The criterion of ipsocentric ring current has been used to assess aromaticity in S-N heterocycles (and related inorganic ring systems). Current density maps indicate that the ten r-electron systems [SsNs], [S4N3] and [S4N4] , and the fourteen r-electron system [S5N5] support diatropic k currents, reinforced by a circulations. 

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