Organolithium reagents, reaction with sulfides

Upon reaction with Grignard reagents or organolithium compounds, mixed sulfides are formed (eq 2). ... 

Unsymmetrically substituted sulfides can be accessed by reactions between sulfenyl derivatives R -S-X [R = alkyl, aryl X = Cl, OCH3, A-imidazolyl] with an organolithium reagent. Organolithiums react with selenium and tellurium compounds e.g., with diphenyl diselenide or with phenyltellurium bromide ) in the same way as with sulfur compounds if sometimes less effectively. 

The reaction of triarylsulfonium salts or diarylsulfoxides with organolithium or Grignard reagents affords diaiylsulfide and biaryl coupling products. The formation of sulfuranes with four carfocm-sulfiir bonds has been postulated for a long time. In 1971, Sheppard reported the detection of tetrakis(penta-fluorophenyl)sulfurane by NMR at low temperature, as an unstable intermediate in the reactions of pentafluorophenyllithium with fluorosulfurane derivatives which afforded decafluorobiphenyl and bis(pentafluorophenyl)sulfide. ... 

---