Salz‐ und Komplexsalz‐Bildung bei Imidverbindungen. (10. Mitteilung über innere Komplexsalze)

Ley, H.; Werner, F.

doi:10.1002/cber.191304603203

Cited by 18 publications

(5 citation statements)

References 16 publications

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“…Schiff also described the analogous behavior of nickel salts towards biuret; comparable products, but of intense yellow color, were isolated and analyzed (333, 336; see also 393-395 and table 11). The results were confirmed by later investigators (223,240,313), but in view of the inadequacy of contemporary valency theory, their interpretation in terms of structural formulas proved difficult. Early ideas concerning the nature of these products are expressed by structures such as LXXXIV (336) or LXXXV (223).…”

Section: The Structure Of Biuret-metal Complexesmentioning

confidence: 53%

“…The simplest copper compound responsible for the violet color of the biuret reaction was first isolated in the pure state by Schiff (333,336) in 1896. The composition of this product, which formed well-defined red leaflets or needles (240,336,395), was correctly determined. Its formation was shown to involve one atom of copper (or nickel; see below), two molecules of biuret, and two molecules of alkali, its molecular formula being given as Cu(OH)2 • 2KOH • 2C2H6N3O2 (333, 336).…”

Section: The Structure Of Biuret-metal Complexesmentioning

confidence: 92%

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Biuret And Related Compounds

Kurzer¹

1956

Chem. Rev.

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Section: The Structure Of Biuret-metal Complexesmentioning

confidence: 53%

Section: The Structure Of Biuret-metal Complexesmentioning

confidence: 92%

Biuret And Related Compounds

Kurzer¹

1956

Chem. Rev.

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“…In the context of this work, the investigation of the influence of the additional binding site at the central nitrogen atom is of predominat interest. Neutral 2:1 N -acylamidine metal complexes were reported by Ley and Werner as early as 1913 . The constitutions of such coordination compounds were established in 1969 as trans complexes by Oehme and Pracejus .…”

Section: Introductionmentioning

confidence: 98%

“…Neutral 2:1 N-acylamidine metal complexes were reported by Ley and Werner as early as 1913. 28 The constitutions of such coordination compounds were established in 1969 as trans complexes by Oehme and Pracejus. 29 Bergman and co-workers published the synthesis of a zirconocene complex featuring a doubly deprotonated Nacylamidine ligand 19 (Scheme 4).…”

Section: ■ Introductionmentioning

confidence: 99%

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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“…Furthermore, conjugation over all five atoms is observed even in the neutral form, and an additional coordination site is offered at the central nitrogen atom. The synthesisof 2:1 N ‐acylamidine/metal complexes was described byLey and Werner in 1913 as a reaction of the ligands withmetal(II) acetates 23. This reaction yielded neutral 2:1 metal complexes with anionic ligands, the structures of which were proven to be trans complexes by Oehme and Pracejus in 1969 24.…”

Section: Introductionmentioning

confidence: 99%

Metallomacrocyclic Complexes by Self‐Assembly of Ni^II and Cu^II Ions and Chelating Bis(N‐acylamidines)

et al. 2012

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Bis(N-acylamidines) 1, which contain various rigid or flexible spacer units with different spatial orientations, are potent bis(bidentate) ligands for the coordination of metal ions. Treatment of 1 with Ni II or Cu II salts gave two 2:2 (3) and four 3:3 (4) metallomacrocycles by self-assembly. The structures of the hitherto unknown products were determined by the geometry of the ligands that incorporate either linear or

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Salz‐ und Komplexsalz‐Bildung bei Imidverbindungen. (10. Mitteilung über innere Komplexsalze)

Cited by 18 publications

References 16 publications

Biuret And Related Compounds

Biuret And Related Compounds

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

Metallomacrocyclic Complexes by Self‐Assembly of Ni^II and Cu^II Ions and Chelating Bis(N‐acylamidines)

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Salz‐ und Komplexsalz‐Bildung bei Imidverbindungen. (10. Mitteilung über innere Komplexsalze)

Cited by 18 publications

References 16 publications

Biuret And Related Compounds

Biuret And Related Compounds

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

Metallomacrocyclic Complexes by Self‐Assembly of NiII and CuII Ions and Chelating Bis(N‐acylamidines)

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Metallomacrocyclic Complexes by Self‐Assembly of Ni^II and Cu^II Ions and Chelating Bis(N‐acylamidines)