Cyclic aryleneazachalcogenenes—VI. Synthesis, crystal and molecular structure of 5,6,7,8-tetrafluoro-1,3,2,4-benzodithiadiazine, a formally antiaromatic stable compound

A Brave New World: The Heteroatom Chemistry of 1,3,2,4‐Benzodithiadiazines and Related Compounds

“…[35] With Ar = 3-HC 6 F 4 , the cyclization proved to be effectively regioselective under the conditions employed, since only one of two possible isomers (Scheme 7) was observed with an isolated yield of 55 %. The preferred direction of the ring-closure is seemingly consistent with the same factors as discussed above for the electrophilic cyclization reaction.…”

“…[29b, 35] With Ar = C 6 F 5 , 1f was obtained in an isolated yield of 54 %. [35] With Ar = 3-HC 6 F 4 , the cyclization proved to be effectively regioselective under the conditions employed, since only one of two possible isomers (Scheme 7) was observed with an isolated yield of 55 %.…”

“…[29b, 31,[35][36][37] According to XRD analysis, the precursor with Ar = 2-HC 6 F 4 and X = S possesses a planar Z,E configuration (with the ArX group in the Z position) in the crystal, [29b] which is similar to that of Ar-X-N=S=N-SiMe 3 (X = S, Se) compounds with hydrocarbon Ar groups. [14,38] …”

“…[23c, 29,35] Of the two crystallographically independent molecules of the 6-Br derivative, one is perfectly planar, whereas the other is bent to 3.1°.…”

“…[23c, 29,35] On going from the solid state to the gas phase, the bond lengths of 1h do not change significantly except for the CN and CS bonds, which shorten slightly. For 1f the situation is different: the CN bond shortens, while the CS, S1N2, and S3N4 bonds lengthen, and the N2S3 bond does not change.…”