Synthesis of allyl- and aryl-iminopyrrolyl complexes of nickel

Abstract

The 2-iminopyrrole ligand precursors 2-C₄H₃NH[(R)CN(2,4,6-C₆H₂Me₃)] (R = H, I; R = Me, II) were synthesised and react with NaH to give the corresponding sodium salts 1 and 2, respectively. Salt 2 reacts with [NiPhBr(PPh₃)₂] to yield [NiPh(acetiminopyrrolyl)(PPh₃)] 3. Ligand precursors II and 2 react, respectively, with equimolar amounts of [NiMe₂(TMEDA)] and [NiBr₂(NCMe)₂] to give [Ni(acetiminopyrrolyl)₂] 4. Both 1 and 2 react with [Ni(η³-C₃H₅)(μ-Br)]₂ to give complexes [Ni(η³-C₃H₅)(iminopyrrolyl)] 5 and 6. The crystal structures of ligand precursor II and of complex 3 are reported and compared. Complex 3 was tested for catalytic activity for the oligomerisation of ethylene and showed only moderate activity.