Abstract: The first member of a new class of stable sulfimides, bis [bis (F-methyl) sulfimide],(CF3) 2S= NN= S (CF3) 2, results from the photolysis of (CF3), S= NC1. The latter is prepared by reacting (CF3) $= NH with ClF in the presence of CsF. Under similar conditions,(CF3) $= NH reacts with SF4 to give (CF,), S= NF.