Bis(aniline–phenolate) complexes of group 4 metals: Coordination chemistry and lactide polymerization catalysis

Stopper, Ayellet; Goldberg, Israel; Kol, Moshe

doi:10.1016/j.inoche.2011.02.014

Cited by 20 publications

(1 citation statement)

References 28 publications

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“…Most likely, on the one hand, in the MALDI‐TOF mass spectrum of an oligomer obtained by non‐symmetric complexes (L 1 )Ti(O i Pr) 2 and (L 2 )Ti(O i Pr) 2 (supporting information, Figures S1 and S2), a series of signals end‐capped with O i Pr group and a hydroxyl group are dominant; meanwhile, the spectrum also reveals two kinds of signals end‐capped with O i Pr group unit. So there are possibly two growing polymer chains due to two O i Pr groups on each metal core which is however similar to the results obtained for bis(anilinephenolate) titanium complexes …”

Section: Resultssupporting

confidence: 83%

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide

Wang

Zhang

Zhao

et al. 2016

Applied Organom Chemis

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= Me, R 4 = OMe, R 5 = t Bu, (L 5 )Ti(O i Pr) 2 ) supported by amine bis(phenolate) ligands were synthesized and characterized using NMR spectroscopy and elemental analysis. The solid-state structure of (L 3 )Ti(O i Pr) 2 was determined using single-crystal X-ray diffraction. (L 1-5 )Ti(O i Pr) 2 were all found to initiate the ring-opening polymerization of L-lactide and rac-lactide in a controlled manner at 110-160°C. As shown by kinetic studies, (L 1 )Ti(O i Pr) 2 polymerized L-lactide faster than did (L 2-5 )Ti(O i Pr) 2 . In addition, good number-average molecular weight and narrow polydispersity index (1.00-1.71) of polymers were also obtained. The microstructure of the polymers and a possible mechanism of coordination-insertion of polymerization were evidenced by MALDI-TOF and 1 H NMR spectra of the polylactides. KEYWORDS amine bis(phenolate) ligands, ring-opening polymerization of lactide, titanium complexes

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Section: Resultssupporting

confidence: 83%

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide

Wang

Zhang

Zhao

et al. 2016

Applied Organom Chemis

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Rational Synthesis of a Family of Neutral Monomeric Heteroleptic Titanium Complexes Based on an Octahedral TiO₄N₂ Motif

et al. 2012

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A rational approach leading to a novel family of monomeric heteroleptic titanium complexes formed with two biphenolate derivatives and six different bidentate nitrogenated chelates is proposed. Only one case of loss of structural predictability was observed in the case of a N,O‐coordinating ligand and led to a structure containing two (μ‐O)‐bridged titanium centres. Diffusion‐ordered NMR spectroscopy (DOSY) measurements have been systematically used to prove that the complexes characterised in the solid state remain identical in the liquid phase. All ligands have also been classified quantitatively according to their electron‐withdrawal capabilities. A quantitative thermodynamic analysis using the PACHA software showed that the entropically favoured displacement of two monodentate‐coordinated alcohol molecules needs to be assisted by solvation of the η2‐chelate product to overcome the enthalpically unfavourable replacement of two highly polar Ti–O bonds by less polar Ti–N bonds. The occurrence of dichloromethane molecules in the crystalline state and the existence of more than one crystallographically nonequivalent complex within the unit cell has been associated with a low dipolar moment of the complexes. Other complexes with large dipolar moments (μ > 2 D) seem to have enough dipolar energy in the solid state to remove all the solvating dichloromethane molecules.

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Aluminum Complexes of Tridentate Amine Biphenolate Ligands Containing Distinct N‐alkyls: Synthesis and Catalytic Ring‐opening Polymerization

Liang

Lin

Chen

2013

J Chinese Chemical Soc

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A series of aluminum complexes of amine biphenolate ligands that contain distinct N-alkyl substituents have been prepared and employed for ring-opening polymerization (ROP) of e-caprolactone (e-CL). Alkane elimination of trimethylaluminum with2-; R = tBu (1a), iPr (1b), nPr (1c)) in toluene solutions at 25°C produces colorless crystalline [R-ONO]AlMe (2a-c). X-ray diffraction studies of these organoaluminum complexes showed them to be four-coordinate species having a distorted tetrahedral coordination core. In the presence of benzyl alcohol, complexes 2a-c are all active catalyst precursors for ROP of e-CL. The ROP rates of e-CL are clearly a function of the steric sizes of the N-alkyl substituents, following an increasing order 2a < 2b < 2c. Interestingly, both 2b and 2c exhibit controlled ROP catalysis whereas 2a gives low molecular weight oligomers under identical conditions. In ROP catalyzed with 2b or 2c, the e-CL disappearance rates follow pseudofirst order kinetics, with the latter being about 2.86(2) times faster than the former. Complex 2b outperforms 2c in view of maintaining controlled ROP catalysis in reactions with extremely high monomerto-catalyst ratios. The complex constitution-reactivity relationship is discussed.

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Bis(aniline–phenolate) complexes of group 4 metals: Coordination chemistry and lactide polymerization catalysis

Cited by 20 publications

References 28 publications

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide

Rational Synthesis of a Family of Neutral Monomeric Heteroleptic Titanium Complexes Based on an Octahedral TiO₄N₂ Motif

Aluminum Complexes of Tridentate Amine Biphenolate Ligands Containing Distinct N‐alkyls: Synthesis and Catalytic Ring‐opening Polymerization

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Bis(aniline–phenolate) complexes of group 4 metals: Coordination chemistry and lactide polymerization catalysis

Cited by 20 publications

References 28 publications

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide

Rational Synthesis of a Family of Neutral Monomeric Heteroleptic Titanium Complexes Based on an Octahedral TiO4N2 Motif

Aluminum Complexes of Tridentate Amine Biphenolate Ligands Containing Distinct N‐alkyls: Synthesis and Catalytic Ring‐opening Polymerization

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Rational Synthesis of a Family of Neutral Monomeric Heteroleptic Titanium Complexes Based on an Octahedral TiO₄N₂ Motif