Diiminopyrrolide copper alkoxide complexes, LCuOR (OR(1)=N,N-dimethylamino ethoxide, OR(2)=2-pyridyl methoxide), are active for the polymerization of rac-lactide at ambient temperature in benzene to yield polymers with M(w)/M(n)=1.0-1.2. X-ray diffraction studies showed bridged dinuclear complexes in the solid state for both complexes. While LCuOR(1) provided only atactic polylactide, LCuOR(2) produced partially isotactic polylactide (P(m)=0.7). The difference in stereocontrol is attributed to a dinuclear active species for LCuOR(2) in contrast to a mononuclear species for LCuOR(1).
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http://dx.doi.org/10.1002/anie.201505674 | DOI Listing |
Inorg Chem
July 2023
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, P.R. China.
Reactions of achiral di(2-pyridyl)methyl substituted aminophenols (2-{-R--[di(2-pyridyl)methyl]aminomethyl}-4-R-6-R-CHOH: R = R = Bu, R = Bu (), R = hexyl (), R = cyclohexyl (); R = R = cumyl, R = Bu (), R = hexyl (), R = cyclohexyl ()) with {Mg[N(SiMe)]} ([]:[Mg] = 1:1) afforded a series of magnesium silylamido complexes -. In the solid state, the magnesium center of , , and is penta-coordinated by the tetradentate aminophenloate ligand and one silylamido ligand to form a seriously distorted square-pyramidal geometry as confirmed by X-ray crystallography diffraction analysis. VT H NMR and ROESY experiments further indicate that these magnesium complexes are also five-coordinated in solutions where the coordination of either of the two pyridyl pendants to the magnesium center is maintained.
View Article and Find Full Text PDFInorg Chem
May 2023
Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB, UMR-CNRS 6302), Université de Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France.
Ethylene- and phenylene-bridged bis(salicylamidine) ligands have been readily prepared from ethylene or phenylenediamine and iminium chloride derivatives generated from ,-dialkylsalicylamides. The former, in its diprotonated form (FAlenH), reacts with AlMe to afford a zwitterionic dimethyldiphenoxyaluminate complex with the FAlen ligand monoprotonated and in a bidentate κ, fashion. A phenylene-bridged proligand behaves differently, yielding a neutral methylaluminum complex bearing a κ,,-coordinated FAlen ligand.
View Article and Find Full Text PDFHeliyon
February 2023
School of Chemistry & Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban, 4000, South Africa.
Synthesis and catalytic studies of aryl carboxylate Zn (II) complexes is reported. Reaction of substituted ()--phenyl-1-(pyridin-4-yl)methanimine with a methanolic solution of Zn(CHCOO) and substituted aryl carboxylate co-ligands gave heteroleptic Zn(II) complexes; [Zn(CHCOO)()] (), [Zn(CHCOO)()] (), [Zn (4-F-CHCOO)()] (), [Zn(CHCOO)()] (), [Zn(CHCOO)()] (), [Zn (4-F-CHCOO)()] (), [Zn(CHCOO)()] (), [Zn(CHCOO)()] (), [Zn (4-F-CHCOO)()] (). The molecular structures of complexes and are dinuclear with the zinc atom in complex adopting a distorted trigonal bipyramidal geometry in a bi-metallacycle while complex is square pyramidal where all four benzoate ligands bridge the zinc metals in a paddle wheel arrangement.
View Article and Find Full Text PDFChem Rec
August 2021
Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India.
The ring-opening polymerization (ROP) of lactide (the dilactone of lactic acid) produces poly(lactide) commonly referred to as poly(lactic acid) (PLA). The monomer lactide, has two stereogenic centers and thus, three stereoisomers are possible, namely: D-(R,R), L-(S,S) and meso-lactide. The rac-lactide is an equimolar mixture of D- and L-enantiomers.
View Article and Find Full Text PDFDalton Trans
April 2021
Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12, Mansfield Road, OX1 3TA, Oxford, UK.
A new family of group 4 permethylpentalene (CMe; Pn*) aryloxide and alkoxide complexes have been synthesised and fully characterised by multinuclear NMR spectroscopy and single-crystal X-ray diffraction; (η-CMe)Zr(OR) (R = Bu (1), 2,6-Me-CH (2), 2,6-Pr-CH (3) and 4-OMe-CH (4)), (η-CMe)Zr (OR) (R = 2,6-Bu-CH (5) and 2,6-Bu-4-Me-CH (6)), (η-CMe)ZrCp(OR) (R = Bu (7), 2,6-Me-CH (8) and 2,6-Pr-CH (9)), (η-CMe)TiCp(O-2,6-Me-CH) (10) and (η-CMe)ZrCp(OR) (R = 2,6-Me-CH (11), 2,6-Pr-CH (12) and 2,4-Bu-CH (13)). 2, 3, 6, 7, 9, 10 and 12 were studied as initiators for the ring-opening polymerisation (ROP) of l-lactide, and 2, 3, 6, 7 and 10 were studied as initiators for the ROP of rac-lactide. 3 was found to be the most active initiator for the ROP of l-lactide (k = 0.
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