Synthesis, structure and ethylene polymerization behavior of zirconium complexes with chelating ketoiminate ligands
摘要:
Mixed ketoiminate/ketoimine/pentamethylcyclopentadienyl (Cp*) complex of zirconium, [(eta (5)-Cp*){CH3C(O)CHC-(NHR)CH3} {CH3C(O)CHC(NR)CH3}ZrCl2] (R = 4-CF3Ph) (3) has been prepared in high yield by the reaction of one equivalent of 4-CF3-phenyl-beta -ketoimine (1a) and one equivalent of lithium 4-CF3-phenyl-beta -ketoiminate (2a) with one equivalent of Cp*ZrCl3 in Et2O. Bis(ketoiminate)zirconium dichloride complexes, 4 and 6, have been also prepared in high yield by the reaction of amine elimination of ketoimine ligands, respectively 1a and 1b, with Zr(NMe2)(4) and followed by chlorination reaction with TMSCl. The X-ray crystallography reveals that the compound 3 is based on distorted octahedral geometry containing a ketoimine and a ketoiminate. The ketoiminate ligand coordinates to the zirconium as a bidentate ligand, leaving the metal center coordinatively unsaturated and thus leading to an additional binding of a ketoimine ligand to the metal to stabilize the complex 3. The zirconium complexes 3, 4 and 6 provide the moderate activity for the polymerization of ethylene in the presence of MMAO cocatalyst. Low molecular weight and high density polyethylene was obtained. (C) 2001 Elsevier Science B.V. All rights reserved.
NMR of Enaminones Part 3—1H,13C and17O NMR Spectroscopic Studies of Acyclic and CyclicN-Aryl Enaminones: Substituent Effects and Intramolecular Hydrogen Bonding
17O, 13C and 1H NMR spectra for para‐ and meta‐substituted 4‐arylaminopent‐3‐en‐2‐ones (acyclic enaminones, 1 and 2) and 3‐arylaminocyclohex‐2‐en‐1‐ones (cyclic enaminones, 3 and 4) are reported. The 17O, 13C and 1H shift values of these enaminones correlate well with σm0 and σp‐ constants in the correlations for meta and para derivatives, and with pKa values of the corresponding anilines. Dual substituent
Visible-Light-Mediated 1,2-Acyl Migration: The Reaction of Secondary Enamino Ketones with Singlet Oxygen
作者:Weigang Fan、Pixu Li
DOI:10.1002/anie.201407413
日期:2014.11.3
Secondary enaminones were oxidized by photochemically generated singlet oxygen, followed by nucleophilic addition of alcohol and an unexpected 1,2‐acyl migration to afford quaternary amino acid derivatives. An ene‐type reaction pathway is proposed. It is distinctively different from the typical [2+2] addition of singlet oxygen to a CC bond pathway.
Electrochemical behaviour of amino substituted β-amino α,β-unsaturated ketones: A computational chemistry and experimental study
作者:Tankiso Lawrence Ngake、Johannes Hermanus Potgieter、Jeanet Conradie
DOI:10.1016/j.electacta.2018.11.144
日期:2019.2
PhCOCHC(NHPh)CF3 (Series 2). The cyclic voltammograms measured in CH3CN, generally exhibit both a chemically and electrochemically irreversible reduction peak between −1.2 V and −3.1 V vs FcH/FcH+, producing an unstable radical anion, for most of these 1,3-amino ketones. Only ligands PhCOCHC(NHPh)CH3, PhCOCHC(NHPh)CF3 and PhCOCHC(NH(p-NO2-Ph))CH3, showed reversible electrochemical behaviour, at higher
Synthesis, structure and ethylene polymerization behavior of zirconium complexes with chelating ketoiminate ligands
作者:Jindong Kim、Jeong-Wook Hwang、Youngjo Kim、Min Hyung Lee、Yonggyu Han、Youngkyu Do
DOI:10.1016/s0022-328x(00)00555-6
日期:2001.2
Mixed ketoiminate/ketoimine/pentamethylcyclopentadienyl (Cp*) complex of zirconium, [(eta (5)-Cp*)CH3C(O)CHC-(NHR)CH3} CH3C(O)CHC(NR)CH3}ZrCl2] (R = 4-CF3Ph) (3) has been prepared in high yield by the reaction of one equivalent of 4-CF3-phenyl-beta -ketoimine (1a) and one equivalent of lithium 4-CF3-phenyl-beta -ketoiminate (2a) with one equivalent of Cp*ZrCl3 in Et2O. Bis(ketoiminate)zirconium dichloride complexes, 4 and 6, have been also prepared in high yield by the reaction of amine elimination of ketoimine ligands, respectively 1a and 1b, with Zr(NMe2)(4) and followed by chlorination reaction with TMSCl. The X-ray crystallography reveals that the compound 3 is based on distorted octahedral geometry containing a ketoimine and a ketoiminate. The ketoiminate ligand coordinates to the zirconium as a bidentate ligand, leaving the metal center coordinatively unsaturated and thus leading to an additional binding of a ketoimine ligand to the metal to stabilize the complex 3. The zirconium complexes 3, 4 and 6 provide the moderate activity for the polymerization of ethylene in the presence of MMAO cocatalyst. Low molecular weight and high density polyethylene was obtained. (C) 2001 Elsevier Science B.V. All rights reserved.