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Imine Ligands (imine + ligand)

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Chemistry	100%

Selected Abstracts

Syntheses, Characterization, and Luminescent Properties of Monoethylzinc Complexes with Anilido,Imine Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2007
Qing Su
Abstract The syntheses of three anilido,imine ligands of the general formula ortho -C6H4(NHAr,)(CH=NAr, [Ar, = 7-(2,4-Me2)C9H4N, Ar, = 2,6-Me2C6H3 (2a); Ar, = 7-(2,4-Me2)C9H4N, Ar,= 2,6-Et2C6H3 (2b); Ar, = 7-(2,4-Me2)C9H4N, Ar,= 2,6- iPr2C6H3 (2c)] and four zinc(II) complexes of the general formula [ortho -C6H4(NHAr,)(CH=NAr,)]ZnEt [Ar, = 7-(2,4-Me2)C9H4N, Ar,= 2,6-Me2C6H3 (3a); Ar, = 7-(2,4-Me2)C9H4N, Ar,= 2,6-Et2C6H3 (3b); Ar, = 7-(2,4-Me2)C9H4N, Ar, = 2,6- iPr2C6H3 (3c); Ar, = 2,6-Me2C6H3, Ar, = 2,6- iPr2C6H3 (3d)] are described. The complexes were synthesized from the reaction of ZnEt2 with corresponding ligands 2 by alkane elimination. All compounds were characterized by elemental analysis and 1H and 13C NMR spectroscopy. The molecular structures of compounds 2a, 2b, 3b, and 3c were determined by single-crystal X-ray crystallography. The X-ray analysis reveals that complexes 3b and 3c exist in the dimeric form with the N atom in the quinolyl ring coordinating to the other Zn atom to make the Zn atoms four coordinate. Luminescent properties of ligands 2a,2d and complexes 3a,3d in both solution and the solid state were studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Syntheses and Crystal Structures of Copper and Silver Complexes with New Imine Ligands , Air-Stable, Photoluminescent CuIN4 Chromophores

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2003
Goutam Kumar Patra
Abstract A series of new imine ligands [1 (C12H12N2S2), 2 (C12H12N2S2), 3 (C24H18N4S2), and 5 (C30H27N7)] have been synthesized (1 and 2 are structural isomers). CuI and AgI complexes of the nonconjugated dithiophene-diimine ligands 1, 2 and the tripodal imine-amine ligand 5 have also been prepared and thoroughly characterized by spectroscopic techniques as well as by X-ray diffraction. In cyclic voltammetry at a glassy carbon milli electrode in anhydrous dichloromethane under dry N2, the corresponding CuI complexes [6 (2C12H12N2S2·CuClO4), 7 (2C12H12N2S2·CuClO4), and 12 (C30H27N7·CuClO4)] show quasi-reversible CuII/I couples with high redox potentials (1.001 V for 6, 0.958 V for 7, and 0.692 V for 12, vs. Ag/AgCl). This indicates that the ,-acid ligands 1, 2, and 5 preferentially stabilize copper(I) over copper(II). The CuIN4 chromophores in the complexes 6, 7, and 12 display photoluminescence in dichloromethane at room temperature. The related silver complexes of the same three ligands 10 (2C12H12N2S2·AgClO4), 11 (2C12H12N2S2·AgClO4), and 13 [C30H27N7·Ag(CH3CN)ClO4] reveal similar structural features but lack specific photophysical properties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Boron-Based Diastereomerism and Enantiomerism in Imine Complexes , Determination of the Absolute Configuration at Boron by CD Spectroscopy

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 31 2008
Manfred Braun
Abstract Boron turns out to be a stable stereogenic center in imine complexes of aryl and alkyl boronates. Diastereomerically pure complexes 7a,c are obtained from chiral imine ligands 5a,b that are derived from the amino alcohol (R)- 4. The configuration at the boron atom is determined by crystal structure analyses. Racemic boronates 10a,c, available from a condensation of aryl boronic acids 6 with the achiral imine ligand 9, can be separated into stable enantiomers by HPLC on a chiral column. The racemization barrier ,G, has been determined to amount to 105,115 kJ,mol,1. The comparison of calculated and measured CD spectra permits to assign unambiguously the absolute configuration to boron in the enantiomeric boronate-imine complex 10a.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Factorial design analysis of the catalytic activity of di-imine copper(II) complexes in the decomposition of hydrogen peroxide

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2001
W. A. Alves
Factorial design analysis was applied to the study of the catalytic activity of di-imine copper(II) complexes, in the decomposition of hydrogen peroxide. The studied complexes show a tridentate imine ligand (apip), derived from 2-acetylpyridine and 2-(2-aminoethyl)pyridine, and a hydroxo or an imidazole group at the fourth coordination site of the copper ion. The factorial design models for both [Cu(apip)imH]2+ and [Cu(apip)OH]+ were similar. Increasing the peroxide concentration from 3.2 × 10,3 to 8.1 × 10,3 mol L,1 resulted in increased oxygen formation. Increasing the pH from 7 to 11 also increased oxygen formation and had an effect about twice as large as the peroxide one. Both complexes also had an important interaction effect between peroxide concentration and pH. However, increasing the catalyst concentration led to a decrease in total oxygen formation. The obtained results were corroborated by further data, achieved by using the usual univariate method, and helped to elucidate equilibrium steps occurring in the studied systems. In very alkaline solutions, the studied [Cu(apip)imH]2+ complex can form the corresponding dinuclear species, [Cu2(apip)2im]3+. While the mononuclear complex proved to be an efficient catalyst in hydrogen peroxide decomposition, the corresponding dinuclear compound seemed to be able to coordinate with the dioxygen molecule, inhibiting its observed release. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 472,479, 2001 [source]

Syntheses, Characterization, and Luminescent Properties of Monoethylzinc Complexes with Anilido,Imine Ligands

Dynamic Behavior of an N -Metalated ,-Enaminoimine Complex , Preparation of N -Phosphanylenamine and ,-Enaminoimine Derivatives

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2003
Alexandrine Maraval
Abstract Variable-temperature NMR spectroscopy of the ,-enaminoimine complex 2 showed a dynamic process which was attributed to an internal fluxional aldimido N -zirconated ,-linear/,-bent structure. Such an internal rearrangement has been previously proposed to occur in these systems but never observed. We have prepared a variety of (N -phosphanyl-,-enamino)imine ligands using the hydrozirconation/transmetalation reaction of malonodinitrile compounds RCH(CN)2 (R = H, PPh2). In addition to their potential uses in coordination chemistry, these systems are good tools for the study of intramolecular hydrogen bonding. The X-ray crystal structure of 14 at 180 K shows an unsymmetrical system with the N(H) proton localized on one of the two chelating nitrogen atoms, consistent with the existence in solution of a low barrier proton transfer process with a double-well potential. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Syntheses and Crystal Structures of Copper and Silver Complexes with New Imine Ligands , Air-Stable, Photoluminescent CuIN4 Chromophores

Boron-Based Diastereomerism and Enantiomerism in Imine Complexes , Determination of the Absolute Configuration at Boron by CD Spectroscopy

A Dynamic Tricopper Double Helicate

CHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2006
Marie Hutin
Abstract The reaction between 8-aminoquinoline, 1,10-phenantholine-2,9-dicarbaldehyde, and copper(I) tetrafluoroborate gave a quantitative yield of a tricopper double helicate. The presence of dynamic covalent imine (CN) bonds allowed this assembly to participate in two reactions not previously known in helicate chemistry: 1) It could be prepared through subcomponent substitution from a dicopper double helicate that contained aniline residues. An electron-poor aniline was quantitatively displaced; a more electron-rich aniline competed effectively with the aminoquinoline, setting up an equilibrium between dicopper and tricopper helicates that could be displaced towards the tricopper through the addition of further copper(I). 2) Both dicopper and tricopper helicates could be prepared simultaneously from a mixture of phenanthroline dialdehyde, aniline, and aminoquinoline, which contained all possible imine condensation products in equilibrium. Following the addition of copper(I), thermodynamic equilibration on both covalent and coordinative levels eliminated all partially-formed and mixed imine ligands from the mixture, leaving the helicates as exclusive products. La réaction entre la 8-aminoquinoline, la 1,10-phenanthroline-2,9-dicarbaldehyde et le cuivre(i,) tetrafluoroborate conduit à la formation quantitative d'un double hélicate à trois cuivres. Grâce à la liaison imine (CN) dynamique et covalente, cet assemblage participe à deux réactions nouvelles dans la chimie des hélicates : 1) L'hélicate peut être préparé par la substitution de composants à partir d'un double hélicate à deux cuivres incorporant des anilines. Une aniline pauvre en électrons est déplacée quantitativement par l'aminoquinoline ; une aniline plus riche en électrons est déplacée plus difficilement, conduisant ainsi à un équilibre entre l'hélicate à deux cuivres et celui à trois cuivres. Cet équilibre peut être déplacé vers la formation de l'hélicate à trois cuivres par l'addition d'un excès de cuivre(i,). 2) Les hélicates à deux et trois cuivres peuvent être préparés simultanément en ajoutant du cuivre(i,) à un mélange d'aminoquinoline, d'aniline et de phenanthrolinecarbaldehyde contenant tous les produits de condensation possibles à l'équilibre. Suite à cet ajout, l'équilibre thermodynamique élimine les ligands partiellement formés ou mixtes, laissant les hélicates comme uniques produits. [source]

Self-assembly of multinuclear complexes with enantiomerically pure chiral binaphthoxy imine ligands: Effect of the alkyl spacer connecting two binaphthyl units on the metal binding

CHIRALITY, Issue 9 2006
Takeshi Maeda
Abstract Metal complexing behavior of enantiomerically pure ,,,-diiminoalkanes possessing the two terminal binaphthyl units (L1 and L2) was studied. The ligands L1 and L2 were prepared by the reaction of optically pure 2,-butoxy-3-formyl-2-hydroxy-1,1,-binaphthyl with propane and pentane diamines. Reactions of L1 and L2 with equimolar amount of Cu(OAc)2 afforded quantitatively multinuclear complexes 1. The structure of 1 was confirmed by MALDI,TOF MS spectroscopy, X-ray single-crystal-structure analysis, and UV/vis and CD spectroscopic analyses. The reaction of L1 having a 1,3-propanediyl spacer resulted in the formation of a self-assembled product, which was assigned as enantiopure trinuclear circular helicate 1a, while the ligand having a 1,5-pentanediyl spacer L2 gave a different self-assembled product, dinuclear side-by-side complex 1b. The circular dichroism (CD) spectrum of 1a in solution showed intense Cotton effects in both the ,,,* transition of the naphthalene units and the LMCT region of the N,O -chelate moieties. The CD spectrum of 1b was completely different from that of 1a; in particular the Cotton effects in the LMCT region were very weak, contrary to those of 1a. These results suggest that 1a retains some chirality induced on the N,O -chelating moieties even in solution, while the induced chirality on the N,O -chelating moieties in 1b is not very significant, being consistent with the consequences of the X-ray single-crystal-structure studies. Chirality, 2006. © 2006 Wiley-Liss, Inc. [source]