Syntheses of Zinc Complexes with Multidentate Nitrogen Ligands: New Catalysts for Aldol Reactions

Darbre, Tamis; Dubs, Christian; Русанов, Эдуард Б.; Stœckli-Evans, Helen

doi:10.1002/1099-0682(200212)2002:12<3284::aid-ejic3284>3.0.co;2-6

Cited by 29 publications

(22 citation statements)

References 8 publications

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“…One consequence of this flexibility is the formation of a six-coordinate Zn complex 5 with a more common octahedral geometry around the Zn(II) ion. Similar ligand flexibility in the formation of various zinc complexes with different coordination numbers, and hence geometries for the pentadentate ligand (2,6-bis{[(pyrid-2-ylmethyl)-amino]methyl}pyridine), was reported by Darbre et al 41 However, for planar rigid pentadentate/heptadentate ligands lacking this flexibility, the formation of zinc(II) complexes with pbp geometry as found for the iron complexes 3 and 4 was reported, e.g., for 2,6-diacetylpyridine imine derivatives. 42 Stereochemistry of the Complexes.…”

Section: Discussionsupporting

confidence: 74%

Diastereopure Fe(II) and Zn(II) Complexes Derived from a Tridentate N,N‘,N-Bis(methyl-l-prolinate)-Substituted Pyridine Ligand

et al. 2006

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A series of mononuclear iron(II) and zinc(II) complexes of the new chiral Py(ProMe) 2 (5) are reported. They all show a meridional NN′N coordination of the Py(ProMe) 2 ligand. The bis-chloride derivatives 1 and 2 represent neutral isostructural five-coordinated complexes with a distorted geometry around the metal center. Unusual sevencoordinate iron(II) complexes 3 and 4 having a pentagonal bipyramidal geometry were obtained using weakly coordinating triflate anions. The reaction of Zn(OTf) 2 with the Py(ProMe) 2 ligand afforded complex 5 with a distorted octahedral geometry around the zinc center. All complexes were formed as single diastereoisomers. In the case of complexes 3−5, the oxygen atoms of both carbonyl groups of the ligand are also coordinated to the metal. The stereochemistry of the coordinated tertiary amine donors in complexes 3−5 is of opposite configuration as in complexes 1 and 2 as a result of the planar penta-coordination of the ligand Py(ProMe) 2 . Complexes 1, 2, and 5 have an overall Λ-configuration at their metal center, while the Fe(II) ion in complexes 3 and 4 has the opposite ∆-configuration (crystal structures and CD measurements). The magnetic moments of iron complexes 1, 3, and 4 correspond to that of high-spin d 6 Fe(II) complexes. The solution structures of complexes 1−5 were characterized by means of UV−vis, IR, conductivity, and CD measurements and their electrochemical behavior. These studies showed that the coordination environment of 1 and 2 observed in the solid state is maintained in solution. In coordinating solvents, the triflate anion (3, 5) or water (4) co-ligands of complexes 3−5 are replaced by solvent molecules with retention of the original pentagonal bipyramidal and octahedral geometry, respectively.

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Section: Discussionsupporting

confidence: 74%

Diastereopure Fe(II) and Zn(II) Complexes Derived from a Tridentate N,N‘,N-Bis(methyl-l-prolinate)-Substituted Pyridine Ligand

et al. 2006

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“…1,1 0 -(Pyridine-2,6-diyl)bis[N-(pyridin-2-ylmethyl)methanaminium] dichloride dihydrate compound was obtained following the procedure previously reported in the literature (Gruenwedel, 1968;Newkome et al, 1984;Darbre et al, 2002;Kobayashi et al, 2006). The procedure used for the synthesis has three steps.…”

Section: Synthesis and Crystallizationmentioning

confidence: 99%

“…Firstly, the synthesis of 2-[(tosylamino)methyl]pyridine was carried out by treatment of 2-(aminomethyl) pyridine with NaOH and tosyl chloride in a two-phase system (water/diethyl ether) (Newkome et al, 1984). In the second step, the coupling of 2-[(tosylamino)methyl] pyridine with 2,6bis(bromomethyl) pyridine, also in an two-phase system (dichloromethane/water) and nBu 4 NBr as phase-transfer catalyst gave 2,6-bis{[(pyrid-2-ylmethyl)(tosyl)amino]methyl}pyridine, which could be isolated after chromatography (Darbre et al, 2002). Finally, the tosylate group of 2,6-bis{[(pyrid-2-ylmethyl)(tosyl)amino]methyl}pyridine was removed using concentrated sulfuric acid for deprotection with heating at 393 K for 3 h to give an unstable brownish oil (Newkome et al, 1984).…”

Section: Synthesis and Crystallizationmentioning

confidence: 99%

Crystal structure of 1,1′-(pyridine-2,6-diyl)bis[N-(pyridin-2-ylmethyl)methanaminium] dichloride dihydrate

Merabet¹,

Tassé²,

Mallet‐Ladeira³

et al. 2021

Acta Cryst E

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In the title compound, C19H23N5 2+·2Cl−·2H2O, the two pyridine side arms are not coplanar, with the terminal pyridine rings subtending a dihedral angle of 26.45 (6)°. In the crystal, hydrogen bonds, intermolecular C—H...Cl contacts and a weak C—H...O interaction connect the molecule with neighbouring chloride counter-anions and lattice water molecules. The crystal packing also features by π–π interactions with centroid-centroid distances of 3.4864 (12) and 3.5129 (13) Å.

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“…The N-methylated pyridylamine ligands 2 and 6 were prepared from the non-methylated precursors. [58][59][60][61][62] The N-methyl carboxamide ligands 3, 4, 7 and 8 were prepared by methylation of the carboxamides, which were obtained by reacting pyridine dicarboxylic acid or acid chloride with the corresponding amine (see Experimental section). N-methyl carboxamides show restricted rotation around the CO-NMe bond, which can lead to 3 rotamers and complicated NMR spectra.…”

Section: Synthesis and Characterisation Of Ligands And Metal Complexesmentioning

confidence: 99%

Unraveling the origins of catalyst degradation in non-heme iron-based alkane oxidation

et al. 2014

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A series of potentially tetradentate and pentadentate ligands modelled on BPMEN has been prepared and their iron(II) bis(triflate) complexes have been isolated and characterised by spectroscopic and crystallographic techniques (BPMEN = N,N'-bis(pyridylmethyl)ethylenediamine). Changes to the BPMEN ligand have invariably led to complexes with different coordination modes or geometries and with inferior catalytic efficiencies for the oxidation of cyclohexane with H2O2. The reaction of an iron(II) complex containing a pentadentate BPMEN-type ligand with O2 has resulted in ligand degradation via oxidative N-dealkylation and the isolation of a bis(hydroxo)-bridged dinuclear iron(III) complex with a picolinate-type ligand.

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Syntheses of Zinc Complexes with Multidentate Nitrogen Ligands: New Catalysts for Aldol Reactions

Cited by 29 publications

References 8 publications

Diastereopure Fe(II) and Zn(II) Complexes Derived from a Tridentate N,N‘,N-Bis(methyl-l-prolinate)-Substituted Pyridine Ligand

Diastereopure Fe(II) and Zn(II) Complexes Derived from a Tridentate N,N‘,N-Bis(methyl-l-prolinate)-Substituted Pyridine Ligand

Crystal structure of 1,1′-(pyridine-2,6-diyl)bis[N-(pyridin-2-ylmethyl)methanaminium] dichloride dihydrate

Unraveling the origins of catalyst degradation in non-heme iron-based alkane oxidation

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