By Halogenation of Carbodiimides

Chlorination of bis-l,2,2,2-tetrachloroethylcarbodiimide affords the perchlorinated compound, which is in the diazadiene configuration 10. Subsequent treatment of 10 with Sbp3 in the presence of a catalytic amount of SbCls gives bis-l,l-difluoro-2,2,2-trichloroethylcarbodiimide 11, bp 68 °C/0.06 Torr, mp 37 °C in 46 % yield.  

Likewise, reaction of diazadiene 12 with CsF gives carbodiimide 13 rather than the expected perfluorinated diazadiene.  

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