Sulfur nitrogen chains, planar

The S3N2O2 molecule is a planar chain of sulfur and nitrogen atoms terminated by oxygen atoms (21) ... 

One would expect that ir bonding would be restricted to the SNSNS chain of atoms and that these would be coplanar, with the middle sulfur atom of the SSS chain flipped out of the plane to allow normal bond angles at all the atoms. Nelson and Heal have shown recently that the physical properties of S4N2 are consistent with a six-membered ring structure with the nitrogen atoms separated by one sulfur atom (25). Although they point out that the data do not permit distinguishing between the possible boat, chair, and planar conformations, they do not even consider the conformation shown above. 

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