Structural properties and applications of multidentate [O,N,O,X′] aminobisphenolate metal complexes

Wichmann, Oula; Sillanpää, Reijo; Lehtonen, Ari

doi:10.1016/j.ccr.2011.09.007

Cited by 96 publications

(54 citation statements)

References 120 publications

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“…Similarity restraints were applied to these disorder components, and sensible anisotropic convergence was achieved. Me,tBu ]} 3 (1). A solution of n-butyllithium (6.50 mL, 10.0 mmol) in hexane was added dropwise to a stirred solution of L1H (2.5 g, 9.0 mmol) in THF (60.00 mL) at −78°C.…”

Section: Experimental Generalmentioning

confidence: 99%

“…1 Various ligands of this type have been used in main group and early transition metal chemistry (including lithium, 2-7 magnesium, [8][9][10][11][12][13][14] calcium, 15 rare-earths, 16,17 zinc, [18][19][20][21][22][23][24][25][26][27] aluminum, [28][29][30] zirconium 31,32 and titanium 33 ). Many of these complexes have been reported to be excellent initiators for the ring-opening polymerization (ROP) of cyclic esters such as lactide and ε-caprolactone.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ring-opening polymerization of ε-caprolactone by lithium piperazinyl-aminephenolate complexes: synthesis, characterization and kinetic studies

et al. 2012

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A series of lithium complexes were prepared from 2(N-piperazinyl-N′-methyl)-2-methylene-4-R′-6-Rphenols ([ONN] RR′ ) and characterized through elemental analysis, 1 H and 13 C{ 1 H} NMR spectroscopy, and X-ray crystallography. Treatment of the ligands with n-butyllithium afforded {Li [ONN] RR′ } 3 [R = Me, R′ = t Bu, (1); R = R′ = t Bu (2); R = R′ = t Am, (3), t Am = C(CH 3 ) 2 CH 2 CH 3 ], with trimetallic structures in the solid-state as shown by single-crystal X-ray diffraction. The reactivity of these complexes in the ring-opening polymerization of ε-caprolactone (ε-CL), as well as the influences of monomer concentration, monomer/Li molar ratio, polymerization temperature and time, was studied. Rates of polymerization were first order with respect to both monomer and lithium concentrations, and activation energies for the reactions were determined. MALDI-TOF MS analysis revealed that transesterification had occurred during the polymerization.

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Section: Experimental Generalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ring-opening polymerization of ε-caprolactone by lithium piperazinyl-aminephenolate complexes: synthesis, characterization and kinetic studies

et al. 2012

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“…Thus, amine-phenolate and related ligands possessing a mixed set of N-and O-donor atoms have emerged as attractive candidates due to their ability to stabilize a wide range of metal centers and the ease of systematic steric manipulation by variation of the backbone and phenol substituents. 9 A number of main-group and transition metal complexes including lithium, [10][11][12][13][14][15][16] magnesium, [17][18][19][20][21][22][23] larger alkaline earths, 24 rare-earths, 25,26 zinc, [27][28][29][30][31][32][33][34][35][36] aluminum, [37][38][39][40][41][42][43][44] , tin, 45 zirconium 46,47 and titanium 48 complexes stabilized by these and related ligands have been prepared and some are effective initiators for ROP of cyclic esters such as lactide and ε-caprolactone (e.g., I-IV, Figure 1). Among the catalysts/initiators studied, aluminum complexes with N,O-chelate and related ligands have attracted much attention due to their high activity and good polymer molecular weight control.…”

Section: Introductionmentioning

confidence: 99%

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

et al. 2012

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Abstract:A series of aluminum methyl and chloride complexes bearing 2(N-piperazinyl-N′-methyl)-2-methylene-4-R′-6-R-phenolate or 2(N-morpholinyl)-2-methylene-4-R′-6-R-phenolate ([ONE R1,R2 ]-) {[ R 1 = t Bu, R 2 = Me, E = NMe (L1); R 1 = R 2 = t Bu, E = NMe (L2); R 1 = R 2 = t Bu, 1 E = O (L3)} ligands were synthesized and characterized through elemental analysis, 1 H, 13 The catalytic activity of complexes 1-3 toward ring-opening polymerization (ROP) of ε-caprolactone was assessed. These complexes are more active than analogous Zn complexes for this reaction but less active than the Zn analogs for ROP of rac-lactide. Characteristics of the polymer as well as polymerization kinetics and mechanism were studied. Polymer end-group analyses were achieved using 1 H NMR spectroscopy and MALDI-TOF MS. Eyring analyses were performed and the activation energies for the reactions were determined, which were significantly lower for 1 and 2 compared with 3. This could be for several reasons: (1) the methylamine (NMe) group of 1 and 2, which is a stronger base than the ether (O) group of 3, might activate the incoming monomer via non-covalent interactions, and/or (2) the ether group is able to temporarily coordinate to the metal center and blocks the vacant coordination site towards incoming monomer, whilst the amine cannot do this. Preliminary studies using 4 and 5 towards copolymerization of cyclohexene oxide with carbon dioxide have been performed. 4 was inactive and 5 afforded polyethercarbonate (66.7% epoxide conversion, polymer contains 54.0% carbonate linkages).

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“…It is well known that N and O donors play a key role in the coordination chemistry because they give the possibility of obtaining chelate compounds with interesting structures and properties [1][2][3][4][5][6]. The O,N-donor Schiff bases have often been used as chelating ligands in the field of coordination chemistry because they readily form stable complexes with most of the transition metals [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, thermal study and some properties of N2O4—donor Schiff base and its Mn(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes

Bartyzel

2016

J Therm Anal Calorim

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The new hexadentate N 2 O 4 Schiff base ligand from condensation of 2,4-hydroxybenzophenone and 1,3-propanediamine has been prepared in methanol and ethanol solutions. The Schiff base synthesized from EtOH contains half molecule of amine per one molecule of ligand in its structure. The complexes were synthesized from the direct reaction of this ligand and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) acetates. The Schiff base and its complexes were characterized by elemental analysis, X-ray crystallographic techniques, spectroscopic (UV-Vis, IR) and thermal (TG, TG-FTIR) methods, molar conductance and magnetic measurements. The complexes, except for Ni(II) compound, similar to the Schiff base are amorphous solids. The Ni(II) complex crystallizes in the monoclinic space group P2 1 /c. The N 2 O 2 coordination geometry around nickel(II) is slightly tetrahedrally distorted square planar. Variable temperature magnetic studies of the paramagnetic complexes show the existence of weak antiferromagnetic [for complexes of manganese(III) and cobalt(II)] and weak ferromagnetic [for copper(II)] interactions. The complexes are stable at ambient temperature. After heating at first they lose solvent molecules (water or methanol), and after that organic part undergoes defragmentation and combustion. Based on the obtained data from the TG-FTIR analysis, the main gaseous products resulting from thermal degradation in nitrogen atmosphere are CO 2 , CO, NH 3 , acetic acid, methane, C 6 H 6 , C 6 H 5 CN and C 6 H 5 CH 3 .

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Structural properties and applications of multidentate [O,N,O,X′] aminobisphenolate metal complexes

Cited by 96 publications

References 120 publications

Ring-opening polymerization of ε-caprolactone by lithium piperazinyl-aminephenolate complexes: synthesis, characterization and kinetic studies

Ring-opening polymerization of ε-caprolactone by lithium piperazinyl-aminephenolate complexes: synthesis, characterization and kinetic studies

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

Synthesis, thermal study and some properties of N2O4—donor Schiff base and its Mn(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes

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