1:1- and 2:1-Copper(II) Complexes From PrimaryN-Acylamidines

Eberhardt, Jan K.; Fröhlich, Roland; Venne-Dunker, Sabine; Würthwein, Ernst‐Ulrich

doi:10.1002/1099-0682(200008)2000:8<1739::aid-ejic1739>3.0.co;2-m

Cited by 14 publications

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“…A first platinum(II) complex of a chelating N -acylamidine was reported by Bokach, Kukushkin, and co-workers . Our group has reported several types of metal complexes formed from primary N -acylamidines and copper(II) or palladium(II) salts. − 1,3,5-Triazapentadienes D , in which the terminal oxygen atom of N -acylamidines is replaced by an imino functionality, show similar coordination properties (Scheme ). − …”

Section: Introductionmentioning

confidence: 93%

“…N -Acylamidines 1 / C (Scheme ) are easily accessible nitrogen-rich mono, bi-, and tridentate ligands for aggregation and metal ion coordination. − They may coordinate either as neutral ligands or in deprotonated form. In comparison with β-imino ketones A and β-diimines B and their metal complexes, the central nitrogen atom at the 3-position influences the electronic properties at the respective binding sites considerably.…”

Section: Introductionmentioning

confidence: 99%

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Catalytically Active N-Acylamidine–Zirconium Complexes: Synthesis, Structures, and Application in Ethylene Polymerization

et al. 2016

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Three novel N-acylamidines 1a−c with varying steric bulk and substitution patterns were synthesized and thoroughly characterized by X-ray diffraction. Compounds 1a and 1b, which contain two additional binding sites located at two pyridine substituents, were treated with equimolar amounts of cyclopentadienylzirconium(IV) trichloride at room temperature. The X-ray data of the resulting coordination compounds 7a and 7b indicate the formation of five-membered metallacycles with one of the pyridine nitrogen atoms and the carbonyl oxygen atom acting as binding sites. For the complexation of ligand 1c, a different route was chosen: 1c was first deprotonated to yield the polymeric potassium compound 8 with a very complex substitution pattern based on O , N, and aromatic interactions with the potassium ions. Transmetalation of 8 with cyclopentadienylzirconium(IV) trichloride gave amidinate complex 9, which is dimeric in the solid state but exists in solution in equilibrium with monomeric species. After addition of methylaluminoxane (MAO), the three novel cyclopentadienylzirconium complexes 7a, 7b, and 9 gave active homogeneous single-site catalysts for the polymerization of ethylene. Of these three systems, 9/MAO turned out to be the most efficient one, showing activities 3−5 times higher than 7a/MAO and 7b/MAO, respectively, and producing polymers with a well-defined "monomodal" molecular weight distribution. An important feature of these materials is their broader distribution in molecular weight (PDI > 3), which is best seen in the products of reactions at 53°C, with a "monomodal" main fraction at higher molecular weight and only small fractions of low molecular weight. ■ INTRODUCTIONAfter more than 30 years, the development of new single-site catalysts for olefin polymerization based on early transition metals continues to be one the fields of highest interest for industry and academia. In recent years, research has been centered on robust and efficient precatalysts that can be synthesized in few steps from common (not exotic) materials with the purpose of making them commercially more attractive.Precatalysts based on bi-, tri-, and tetradentate ligands in which carbon, nitrogen, or oxygen atoms efficiently stabilize an early transition metal are worth mentioning (Scheme 1). The advantage of such ligands is the easy access and great control of the steric and electronic environment of the atoms that coordinate the metal, characteristics that are essential for having access to thermally more stable and efficient catalysts in olefin homo-and copolymerization reactions. Among others, reviews 1−4 and articles from the groups of Edelmann, 5 Sita, 6 Hagadorn, 7 Eisen, 8 Rausch, 9 Green, 10 Lappert, 11 Kretschmer and Kempe, 12 and Jin 13 describe the work in this challenging field and deserve special attention.A second strategy to achieve greater competitiveness of the systems based on early transition metals has focused on reducing or eliminating the dependence of these systems on the use of methylaluminoxane (MAO) as an alk...

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Catalytically Active N-Acylamidine–Zirconium Complexes: Synthesis, Structures, and Application in Ethylene Polymerization

et al. 2016

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Polydonor-Substituted 1-Oxa- and 1-Thia-3,5-diazahexatrienes: Synthesis, Structures, Ring−Chain Tautomerism and Theoretical Calculations

2001

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Previously unknown 1-oxa-2,4-diazahexatrienes 1a,b and c, substituted with alkoxy groups, have been prepared by carboxylation of N-alkylideneisoureas 2 with chloroformates 5. Xray analyses of compounds 1b and c show nonplanar, openchain structures. In contrast, thiocarboxylation of 2 with thiochloroformate 6 leads to the spiro compounds 7-ring, as verified by spectroscopic data and X-ray analysis. A tetradonor-substituted 1-oxa-2,4-diazahexatriene 1d was obtained from the reaction of the 1-oxa-3-aza-butadiene 10 with the triply donor-substituted carbenium ion 9. Attempts at further chain elongation of 1a by an alkylation/condensa-

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A Tetranuclear Hydroxo‐Bridged Copper(II) Complex with PrimaryN‐Acylamidines as Ligands: Preparation, Structural, and Magnetic Characterisation

et al. 2005

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The reaction of N‐pivaloylbenzamidine (1a) and tetrakis(acetonitrile)copper(I) hexafluorophosphate in the presence of air yields a hydroxo‐bridged copper(II) complex (4). The product was characterised by X‐ray diffraction analysis and found to be a cubane‐like dimeric complex consisting of two square dimers with the formula [{(1a)2Cu2(OH)2}2](PF6)4·4 CH2Cl2 (4·4 CH2Cl2) with cupric ions and hydroxyl oxygen atoms at alternating vertices of a cube. The complex can be described as consisting of two [ligand‐Cu‐(OH)2‐Cu‐ligand] units held together by long out‐of‐plane Cu–O bonds, creating a tetrameric entity with a Cu4(OH)4 core. Each cupric ion is essentially square‐pyramidally coordinated, being bound to three OH bridges, one N atom of the amidine and one N‐acylamidine O atom. The magnetic properties of this compound have been studied in the 2–300 K temperature range. The measurements revealed that the cupric ions in the cube are antiferromagnetically coupled. This observation has been rationalised on the basis of the structural data. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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1:1- and 2:1-Copper(II) Complexes From PrimaryN-Acylamidines

Cited by 14 publications

References 6 publications

Catalytically Active N-Acylamidine–Zirconium Complexes: Synthesis, Structures, and Application in Ethylene Polymerization

Catalytically Active N-Acylamidine–Zirconium Complexes: Synthesis, Structures, and Application in Ethylene Polymerization

Polydonor-Substituted 1-Oxa- and 1-Thia-3,5-diazahexatrienes: Synthesis, Structures, Ring−Chain Tautomerism and Theoretical Calculations

A Tetranuclear Hydroxo‐Bridged Copper(II) Complex with PrimaryN‐Acylamidines as Ligands: Preparation, Structural, and Magnetic Characterisation

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