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Four new 1,4-diaza-2,3-dimethylbutadiene ligands (Ar-NdC(CH 3 )-(H 3 C)CdNAr; Ar: 3a ) 2,6-diphenylphenyl; 3b ) 2,6-di(4-OCH 3 -phenyl)phenyl; 3c ) 2,6-di(4-tert-butyl-phenyl)phenyl; 3d ) 2,6-di(3,5-dimethylphenyl)phenyl) as well as the palladium dichloride complexes 4a-c and methyl monochloride derivatives 5a-c were prepared, and their polymerization behavior was investigated. The corresponding nickel species 6a-c were tested for the insertion polymerization of ethene by in situ reactions of 3a-c with (DME)NiBr 2 . The ligands are accessible by a three-step procedure. Aryl boronic acids were prepared by Grignard reactions of substituted aryl bromides and were coupled with 2,6-dibromo aniline according to a Suzuki cross-coupling protocol to give the corresponding terphenyl anilines 2a-d. Condensation of 2,3-butanedione with the corresponding aniline afforded the formation of the diimines 3a-d. The corresponding palladium dichloride complexes 4a-c are accessible by reaction with (PhCN) 2 PdCl 2 . The structures of 4a-c could be determined by X-ray analysis. While the terphenyl complex 4a adopts a C 2v -symmetry, 4c exists in a chiral C 2symmetric coordination geometry, due to the repulsive interactions of the sterically demanding tert-butylphenyl substituents of the aniline moieties. All palladium and nickel complexes are catalysts for the polymerization of ethene. However, the chiral Ni(II) complex 6c shows by far the highest polymerization activity up to 2 × 10 4 kg(PE) [mol (Ni) h] -1 . The polyethenes obtained with the palladium methyl monochloro catalysts activated with Na-[(3,5-(CF 3 ) 2 C 6 H 3 ) 4 B] and the nickel dibromo complexes activated with MAO are linear and show in the case of the Ni(II) derivatives molecular weights up to 4.5 × 10 6 g mol -1 (M w /M n ≈ 2), which can be controlled by addition of hydrogen.

The reaction of M(hfac)2 with the tridentate Schiff base H2L (where H2L stands for the 1:1 condensation product of 2‐imidazolecarboxaldehyde with β‐alanine) leads to the complexes [M(HL)(hfac)]n [M = MnII, NiII, and CuII; hfac = hexafluoroacetylacetonate anion] (1–3). The structures of the complexes 1 and 3 have been solved by X‐ray crystallographic methods. The structures are very similar and consist of infinite zig‐zag chains, running parallel to the b axis, in which the metal ions are bridged sequentially by anti‐anti carboxylate groups with intrachain metal–metal distances of 6.134 Å for 1 and 6.239 Å for 3. Each monodeprotonated HL ligand acts as a tridentate one to a metal(II) ion and as a monodentate one to a neighbouring metal(II) centre. Metal atoms exhibit distorted octahedral coordination spheres comprised of two oxygen atoms from the hexafluoroacetylacetonate ligand, three donor atoms from the HL ligand and the oxygen atom belonging to the carboxylate group of an adjacent molecule. The complexes 1–3 have been confirmed to be isomorphous and isostructural on the basis of X‐ray powder diffraction and IR spectra. The magnetic properties of the three compounds were studied by susceptibility measurements as a function of the temperature and successfully analyzed in terms of the isotropic spin Hamiltonian for one‐dimensional infinite chain systems to give the coupling parameters J = –0.91 cm−1, g = 2.03 (1); J = –13.2 cm−1, g = 2.24 (2); and J = 0.40 cm−1, g = 2.11 (3). The magnetic behaviour for all three complexes can be satisfactorily explained in terms of the conformation of the bridge and the interaction between the d orbitals of the metal centre and the bridge.

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Synthesis of new palladium(II) (1), nickel(II) (2a and 2b), and cobalt(II) (3) complexes bearing the unsymmetrical, bidentate nitrogen ligand 2,6‐bis(1‐methylethyl)‐N‐(2‐pyridinylmethylene)phenylamine (L) is described. The solid‐state structures of 1, 2a, and 2b have been determined by single‐crystal X‐ray diffraction. The PdII compound exists in the monomeric form whereas the nickel complexes were observed as centrosymmetric dimers with slightly distorted square‐pyramidal coordination sphere around each nickel center.