2= 4. The structure shows that the nitrogen and sulfur atoms, the S-phenyl ring, and the nitro group are almost in the same plane, while the N-phenyl ring is 90.7" twisted from the coplane. The SN bond distance found for 2a is 1.605 (8) A, which lies between the typical SN single and double bond distances. This intermediate bond distance is interpreted in terms of the formation of a three-electron bond between the nitrogen and sulfur atoms.
