Structural diversity in substituted aminosilyl‐aminopyridinate metal (Zr or Fe) complexes: Synthesis, structures, and ethylene polymerization. (23rd March 2021)

• Record Type: Journal Article
• Authors: Duan, Xin‐E; Zhang, Xiao‐Xia; Liu, Tian; Bai, Sheng‐Di; Tong, Hongbo; Chao, Jian‐Bin; Sun, Wen‐Hua
• Is Part Of: Applied organometallic chemistry. Volume 35:Number 7(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-23
• Subjects: ethylene polymerization -- substituent effects -- tridentate nitrogen ligands -- X‐ray crystal structure -- zirconium and iron complexes; Organometallic chemistry -- Periodicals; Organometallic compounds -- Periodicals; 547.05
• DOI: 10.1002/aoc.6240
• Languages: English
• ISSNs: 0268-2605

Abstract

Abstract : Seven examples of chlorozirconium N ‐[( N, N ‐dimethylamino)dimethylsilyl]‐2‐pyridylaminates, mononuclear monoligand Zr[(RC5 H4 N)NSiMe2 NMe2 ]Cl3 LiCl(Et2 O)2 ( R = 4‐Me, Zr1 ; R = 5‐Me, Zr2 ; R = 5‐Cl, Zr3 ), chloro‐bridged dinuclear diligand [Zr{(RC5 H4 N)NSiMe2 NMe2 }Cl3 ]2 ( R = 5‐Cl, Zr4 ; R = 4‐Cl, Zr5 ), and mononuclear triligand Zr[(RC5 H4 N)NSiMe2 NMe2 ]3 Cl ( R = 6‐Me, Zr6 ; R = H, Zr7 ), have been prepared by the individual reactions of zirconium tetrachloride with the corresponding lithium N ‐[( N, N ‐dimethylamino)dimethylsilyl]‐2‐pyridylaminates of (RC5 H4 N)NHSiMe2 NMe2 ( R = 4‐Me, 1a ; 5‐Me, 1b ; 5‐Cl, 1c ; 4‐Cl, 1d ; 6‐Me, 1e ; H, 1f ), respectively. Besides seven coordination around zirconium core, Zr1 –Zr5 adopt a distorted pentagonal bipyramid geometry with the ligand acting as a monoanionic η 2 :η 1 ‐tridentate fashion; Zr6 –Zr7 present capped trigonal prism geometry with the ligand as η 2 ‐coordination with a pendant N (CH3 )2 free. Extensively, the reactions of FeCl2 with lithiated (RC5 H4 N)NHSiMe2 NMe2 ( R = 4‐Me, 1a ; 5‐Cl, 1c ; 6‐Me, 1e ) afford the corresponding dimeric complexes ( R = 4‐Me, Fe1 ; 5‐Cl, Fe2 ; 6‐Me, Fe3 ), in which Fe1 and Fe2 exhibit C 2 symmetry with each iron unit as a distorted trigonal bipyramidal geometry, while Fe3 specially possesses a centrosymmetric hour‐glass‐shaped core with each iron center as a distorted tetrahedral geometry. Upon activation with methylaluminoxane (MAO), zirconium complexes exhibit moderate to good activities toward ethylene polymerization and produce the polyethylenes with high molecular weight and broad dispersity. Abstract : Sterically and electronically tuning tridentate aminosilyl‐aminopyridinate zirconium and iron complexes were synthesized and characterized. Influences of substituents and location significantly affected the diversity of coordination modes around metal ions along with solvents. The zirconium complexes showed good activities toward ethylene polymerization producing high molecular weight polyethylenes.