Tetrathioethylenes and Related Compounds

Tetra(ethylthio)allene, (EtS)2C=C=C(SEt)2, undergoes a cycloaddition reaction with ArSOa NCO or with an aryl isothiocyanate. However, though allenes are not directly comparable with ethylenes in many respects, further studies are likely to clarify the structural requirements for tetra-thioethylenes to show minimal electrophilic and dienophilic reactivity. 

and tris-(phenylseleno)methyl-lithium compounds have been prepared. They are the first representatives of their class, and early results suggest that the PhSe group stabilizes an adjacent carbanion centre nearly as well as PhS. 

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