Synthesis and Structural Diversity of Group 4 Metal Complexes with Multidentate Tethered Phenoxy-Amidine and Phenoxy-Amidinate Ligands - Université de Rennes Accéder directement au contenu
Article Dans Une Revue Organometallics Année : 2012

Synthesis and Structural Diversity of Group 4 Metal Complexes with Multidentate Tethered Phenoxy-Amidine and Phenoxy-Amidinate Ligands

Résumé

The coordination chemistry of the multidentate tethered amidine-phenol {4,6-tBu2C6H2O(2-C(NR)═NR}H2 ({LONR}H2, R = iPr, 2,6-iPr2C6H3 (Ar)) and new guanidine-phenol {4,6-tBu2C6H2ON(C6H5)(2-C(NR)═NR}H2 ({LON(Ph)NiPr}H2) pro-ligands with group 4 metals has been studied. σ-Bond and salt metathesis reactions were explored to coordinate these (pro)ligands onto zirconium and hafnium. Alkane elimination reactions between {LONR}H2 and Zr(CH2Ph)4 afforded mixed-ligand monobenzyl {LOHNR}{LONR}Zr(CH2Ph) (R = iPr; 1) and monoligand tribenzyl {LOHNAr}Zr(CH2Ph)3 (R = Ar; 2) complexes, respectively. Alkane and amine elimination reactions between {LON(Ph)NiPr}H2 and Zr(CH2Ph)4 or Hf(NMe2)4 unexpectedly resulted in cleavage of the ligand backbone and eventual isolation of {(Ph)NC6H2(tBu)2O}Zr{(iPrN)2CCH2Ph}2 (3) and {(Ph)NC6H2(tBu)2O}Hf{(iPrN)2CNMe2}2 (4), respectively. Salt metathesis reactions between {LONR}Li2 and ZrCl4(THF)n (n = 0, 2), conducted in 1:1 ratios, led upon crystallization to diverse chloro complexes: [{LONiPr}ZrCl]3(μ3-O)(μ3-Cl) (5), [{LONAr}2ZrCl(μ2-Cl)]2[{LHONAr}ZrCl(μ2-Cl)](μ3-OH) (6), and {LOHNAr}ZrCl3(THF) (7). Similar salt metathesis reactions between the monolithium salts {LHONR}Li and ZrCl4, conducted in 2:1 ratios, allowed the selective preparation of bis(phenoxy-amidine) complexes with pendant amino groups {LOHNR}2ZrCl2 (R = iPr, 8; R = Ar, 9). All complexes were authenticated by elemental analysis, X-ray crystallography, and NMR spectroscopy. Complexes 5, 6, 8, and 9, upon activation with MAO, showed poor to moderate productivities (4-172 (kg of PE) mol-1 h-1) in the polymerization of ethylene, giving linear polymers with large polydispersities.

Domaines

Catalyse
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Dates et versions

hal-00874360 , version 1 (17-10-2013)

Identifiants

Citer

Evgeny Kirillov, Thierry Roisnel, Jean-François Carpentier. Synthesis and Structural Diversity of Group 4 Metal Complexes with Multidentate Tethered Phenoxy-Amidine and Phenoxy-Amidinate Ligands. Organometallics, 2012, 31 (8), pp.3228-3240. ⟨10.1021/om300076j⟩. ⟨hal-00874360⟩
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