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

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.