which is either (P h3P) ,bt C (CF,),*NH*C (CF,) , * b or its isomer ( Ph3P)2PtC(CF3),*O*C (CF,),*NH. Moreover, NiL, [L, = 1,2-(Me,As),C,H,] reacts with hexduoroacetone or hexafluoroisopropylideneamine to form L,lkiC(CF,),*X*C(CF,),*;? (X = 0 or NH, respectively) .1These observations suggest activation of co-ordinated (CF,),C=X (X = 0 or NH). It is clear that both the metal and the co-ordinated ligands can have an effect on the extent of ' activation,' and with a view to understanding these reactions more fully we have investigated 3to &membered ring-expansion reactions with isocyanide-nickel complexes. The new compounds obtained were characterised by elemental analysis, i.r.