The reaction of 2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L2) or 4-tert-butyl-2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L3) with iron(ii) precursors produced either iron(ii) or iron(iii) complexes, depending on the nature of the anions in the iron(ii) precursor and the ligand. When the anion is chloride and the ligand L1, the product is [(L1)2Fe][FeCl4] (1), but when the anion is triflate (OTf(-)) and the ligand is L2, the product is [(L2)2Fe][OTf]2 (2). With iron(ii) halides and tert-butyl groups on the phenoxy ligands L2 and L3, the iron(iii) complexes [(L2)FeX2] {where X = Cl (3), Br (4) and I = (5)} and [(L3)FeCl2] (6) were formed. Complexes 1-6 were characterised by a combination of elemental analyses, IR spectroscopy and mass spectrometry; and in selected cases (3 and 4) by single crystal X-ray crystallography. The crystal structures of 3 and 4 indicated that the iron(ii) precursors oxidised to iron(iii) in forming complexes 3-6; an observation that was corroborated by the magnetic properties and the (57)Fe Mössbauer spectra of 3 and 4. The iron(iii) complexes 3-6 were used as pre-catalysts for the oligomerisation and polymerisation of ethylene. Products of these ethylene reactions depended on the solvent used. In toluene ethylene oligomerised mainly to 1-butene and was followed by the 1-butene alkylating the solvent to form butyl-toluenes via a Friedel-Crafts alkylation reaction. In chlorobenzene, ethylene oligomerised mainly to a mixture of C4-C12 alkenes. Interestingly small amounts of butyl-chlorobenzenes and hexyl-chlorobenzenes were also formed via a Friedel-Crafts alkylation with butenes and hexenes from the oligomerisation of ethylene.

A series of discrete chromium(III) precatalysts, {[Cr(κ3‐L1)] (1a.7H2O), {[Cr(κ3‐L2)] (2a.5H2O), {[Cr(κ3‐L3)] (3a.6H2O), {[Cr(κ3‐L4)] (4a.10H2O), {[Cr(κ3‐L5)] (5a.4H2O) and in‐situ‐generated chromium(III) precatalysts {[Cr(κ3‐L1)] (1b), {[Cr(κ3‐L2)] (2b), {[Cr(κ3‐L3)] (3b), {[Cr(κ3‐L4)] (4b), {[Cr(κ3‐L5)] (5b) bearing 2,4‐di‐tert‐butyl‐6‐{[2‐(1H‐imidazol‐4‐yl)‐ethylimino]‐methyl}‐phenol (L1), 2,4‐di‐tert‐butyl‐6‐{[2‐RR‐pyrazol‐1‐yl‐ethylimino]‐methyl}‐phenol, R = H (L2), Me (L3), Ph (L4), and 2,4‐di‐tert‐butyl‐6‐{[2‐pyrid‐2‐yl‐ethylimino]‐methyl}‐phenol (L5) are developed. The discrete precatalysts are characterized by IR spectroscopy, elemental analysis, and mass spectrometry. The in‐situ‐generated precatalysts afford a one‐step process for screening chromium(III) complexes as ethylene polymerization catalysts. Upon activation with EtAlCl2, both types of precatalysts exhibit high catalytic activities up to 1.71 × 105 g mol(Cr)−1 h−1 for the formation of high‐density polyethylene with molecular weights as high as 3.48 × 103 g mol−1. While the discrete precatalysts produce monomodal active catalysts at all conditions, the in‐situ‐generated precatalysts produce either monomodal or bimodal active catalysts, suggesting that, at certain conditions, two active catalysts are produced in the in situ reactions.

Abstract:Five new iron(III) 1-hexene polymerisation catalysts were prepared from the reactions of

In the title compound, (C2H8NO)2[PdCl4], 2-hy­droxy­ethanaminium cations and tetra­chloridopalladate(II) dianions crystallize in a 2:1 ratio with the anion residing on a crystallographic inversion center. The cations and anions are linked in a complex three-dimensional framework by three types of strong hydrogen bonds (N—H⋯O, N—H⋯Cl, and O—H⋯Cl), which form various ring and chain patterns of up to the ternary graph-set level.