S7NH

From the initial view ('Reload Script' if necessary) click on 'Stick View', so that you may see bond angles more clearly, then on 'Rotate 90 deg about screen y', so as to see the molecule in profile.   You now can see that the nitrogen is almost but not quite planar.

We associate planar nitrogen with amides, in which the lone pair on nitrogen is delocalised into a π - bond to an adjacent acyl centre, reducing the basicity of the nitrogen and making the amide proton acidic.

At first sight, a ring of sulfur atoms in which the formal oxidation state of the sulfur adjacent to nitrogen is at most +1, might not be considered as an acyl group, but this is how it behaves.   S7NH is not basic, but is sufficiently acidic for a potassium salt to be made, or for it to react with PhHgOAc to make S7NHgPh, from which further S7N derivatives may be made.

One explanation for the near-planarity of nitrogen, and the lack of basicity of its lone pair, lies in pπ-(σ*)π bonding to the adjacent sulfur atoms.   (See the Comments for the S7 molecule, for a discussion of this.)  

It may be seen that the S-S bonds adjacent to the imide group are not longer than the others in the ring. Their σ* orbitals have slightly higher occupancy than the other S-S σ* orbitals in the ring, but these bonds also are more strengthened by π bonding than the others, so the effects balance out.   If it were not for pπ-(σ*)π bonding, they might otherwise have been expected to be shorter, because of the electronegativity of the nitrogen, which is greater than that of sulfur, making for denser orbitals on the adjacent sulfur atoms, and better σ overlap with their neighbours.