Bimetallic nickel complexes of macrocyclic tetraiminodiphenols and their ethylene polymerization

Schiff’s base condensation of 2,6-diformyl-4-R-phenol and 4,4″-diamino-3,3″,5,5″-R4′-o-terphenyl affords 34-membered macrocyclic tetraiminodiphenol compounds, o-C6H4{(R2′C6H2)–NCH–[RC6H2(OH)]–HCN(R2′C6H2)}2(o-C6H4) (R = H and R′ = iPr, 1; R = Me and R′ = iPr, 2; R = F and R′ = iPr, 3; R = Me and R′ = Et, 4; R = F and R′ = Et, 5) in good yields (47–62%), from which dinuclear nickel complexes, o-C6H4{[(R2′C6H2)–NCH–(RC6H2-O)–HCN(R2′C6H2)-κ2-N,O]Ni(η1-CH2Ph)(PMe3)}2(o-C6H4) (R = H and R′ =  iPr, 6; R = Me and R′ = iPr, 7; R = F and R′ = iPr, 8) are prepared. Molecular structures of 2, dipotassium salt of 1, and 7 were confirmed by X-ray crystallography. Addition of B(C6F5)3 to a toluene solution of 6–8 gives insoluble precipitates which show good activity for ethylene polymerization.

Graphical abstract34-Membered macrocyclic compounds of tetraiminophenol and their bimetallic nickel complexes are prepared. The nickel complexes show good activity for ethylene polymerization.Figure optionsDownload full-size imageDownload as PowerPoint slide