Modular Routes Towards New N,O‐Bidentate Ligands Containing an Electronically Delocalised β‐Enaminone Chelating Backbone

Abstract

Polyketones are synthesised by a transition‐metal‐catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O‐chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised β‐enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO®‐like arsenal of reactions to versatile substituted β‐enaminone ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Bidentate and Tetradentate β‐Aminovinyl Trifluoromethylated Ketones and Their Copper(II) Complexes: Synthesis, Characterization and Redox Chemistry

“…[6][7][8] β-Aminovinyl ketones with a fluoroalkyl moiety are interesting organic precursors that can be decorated in a number of useful synthetic sequences to produce diverse molecular entities with specific applications. [1,[9][10][11][12][13][14][15][16][17][18][19][20][21] Their potentially broad coordination chemistry [21][22][23][24][25][26][27][28][29] combined with appropriate organic functionalities make them attractive for the design of a new generation of original materials with potential in catalysis, molecular magnetism and therapeutic applications. A series of fluorinated enaminones that bear two independent coordination centres have been obtained, and the crystal structure of a Cu II complex has been reported.…”

Square‐Planar 2‐Toluenido(triphenylphosphane)nickel(II) Complexes Containing Bidentate N,O Ligands: An Example of Planar Chirality

“…Remarkably, when using the nonfluorinated cyclohexanecarbonyl chloride (for comparative studies) in this reaction, we found that only N-acylation took place to yield the unwanted [1-cyclohexanecarbonylpyrrolidin-(2E)-ylidene]acetonitrile. [12] Hence, the nonfluorinated analogue of HL 3 remains inaccessible by this method. The complexation of (L 3 ) -to yield the desired nickel complexes 7 or 8 is accomplished by reacting stoichiometric amounts of HL 3 with (SP- (2), respectively, in the presence of sodium bis(trimethylsilyl)-amide as base.…”

“…We reported the syntheses of such bidentate N,O ligands containing an electronically delocalised β-enaminonic chelating backbone in a recent paper. [12] The ligands used in this investigation are summarised in Table 1, and the corresponding nickel complexes are shown in Table 2. Complex 3 is already known and structurally characterised.…”

“…Isotropic displacement parameters of the H atoms were kept equal to 150, 130 and 120 % of the equivalent isotropic displacement parameters of the parent primary, secondary and "aromatic" carbon atoms, respectively. [12] (540 mg, 5 mmol) was dissolved in toluene (50 mL), and triethylamine (505 mg, 5 mmol) was added. The mixture was cooled in an ice bath and 1,2,2,3,3,4,4,5,5,6,6-undecafluorocyclohexanecarbonyl chloride (1.72 g, 5 mmol) was added dropwise with stirring.…”

“…[23][24][25] The preparation of pyrrolidin-(2E/2Z)-ylideneacetonitrile and the ligands 4,4,5,5,6,6,6-heptafluoro-3-oxo-2-pyrrolidin-(2Z)-ylidenehexanenitrile (HL 1 ), 3-oxo-2-pyrrolidin-(2Z)-ylidenehexanenitrile (HL 2 ) and 2-[1-amino-eth-(Z)-ylidene]-4,4,5,5,6,6,6-heptafluoro-3-oxo-hexanenitrile (HL 4 ) was reported previously. [12] Crystal Structure Determinations: Crystals of compounds 7·C 7 H 8 and 10·0.5C 5 H 12 suitable for X-ray study were investigated with a STOE Imaging Plate Diffraction System using graphite-monochromatised Mo-K α radiation (λ = 0.71073 Å). Unit cell parameters were determined by least-squares refinements on the positions of 4225 and 5997 reflections in the range 2.00°Ͻ θ Ͻ 25.20 and 2.05°Ͻ θ Ͻ 24.0°, respectively.…”