Hexafluoroacetone and hexafluorothioacetone nickel complexes

Abstract

Bis(cyclo-octa-1,5-diene)nickel reacts with hexafluoroacetone to give orange crystalline (1,5-C₈H₁₂)Ni[(CF₃)₂CO]. The diene ligand is readily displayed by tertiary phosphines, phosphites, and dipyridyl forming stable complexes L₂Ni[(CF₃)₂CO] where L is Ph₂PMe, (PhO)₃P, and EtC(CH₂O)₃P; or where L₂ is [Ph₂PCH₂]₂ or dipyridyl. Treatment of (1,5-C₈H₁₂)₂Ni with methyldiphenylphosphine gives (Ph₂PMe)₄Ni, which reacts with hexafluoroacetone affording a complex identical with that obtained by the ligand displacement reaction. The complex (Et₃P)₂Ni[(CF₃)₂CO] was similarly prepared from (Et₃P)₄Ni. The compound (1,5-C₈H₁₂)Ni[(CF₃)₂CS] is formed by treating (1,5-C₈H₁₂)₂Ni with 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietan at 0°. Ligand displacement reactions give the stable complexes L₂Ni[(CF₃)₂CS], where L is Ph₃P, (PhO)₃P, or EtC(CH₂O)₃P; or where L₂ is [Ph₂PCH₂]₂ or dipyridyl.

Examination of the ¹H and ¹¹F n.m.r. and i.r. spectra of the compounds suggests that they are best depicted as nickel(II) complexes, in which the metal is part of a rigid three-membered ring.