Synthesis and characterisation of κ ²- N, O-oxazoline-enolate complexes of nickel(ii): explorations in coordination chemistry and metal-mediated polymerisation†‡

Abstract

The synthesis and characterisation (UV-Vis, IR, X-ray diffraction, etc.) of a series of Ni( ii) complexes derived from both known and novel 2-acylmethyl-2-oxazolines (2a–g: i.e., ( Z)-1-R-2-(4,4′-dimethyl-2′-oxazolin-2′-yl)eth-1-en-1-ol; R = –Ph, –2-furanyl, – p-NO ₂-Ph, – t-Bu, –2-thiofuranyl, p-NC-Ph, –CF ₃) is reported. These Ni materials (3a–g) represent the first group 10 metal complexes of this ligand class. All derivatives reported are paramagnetic ( S = 1) compounds of formulae Ni(κ ²- N, O-L) ₂ where L represents an enolate of structure ( Z)-1-R-2-(4′,4′-dimethyl-2′-oxazolin-2′-yl)eth-1-en-1-ate formed via proton loss from 2. The air- and moisture-stable metal complexes feature a less typical distorted seesaw-shaped disposition of binding atoms around the metal centre for six structurally characterised (X-ray) examples. Preliminary investigations indicate that 3a (R = –Ph) is a useful catalysts for olefin polymerisation in the presence of alkylaluminum reagents.

Abstract

Novel Ni( ii) enolate complexes derived from ( Z)-1-R-2-(4′,4′-dimethyl-2′-oxazolin-2′-yl)eth-1-en-1-ols are synthesised and structurally examined. The complexes display good potency as olefin polymerisation catalysts.