Manganese, iron and cobalt complexes bearing multidentate ligand sets : catalysts for ethylene oligomerisation/polymerisation
In Chapter Two, the synthesis and coordination behaviour of the aryl-substituted N-picolyethylenediamines and N-bis(picolyl)ethylenediamines along with bis(2-picolyl)amine, tris(2-picolyl)amine in manganese(II), iron(II) cobalt(II) complexes are reported. The notable influence of steric effects upon the nuclearity and the binding mode is described. The flexibility of the N-picolyl-en systems when coordinated to iron or cobalt is observed by single crystal X-ray diffraction studies, paramagnetic 1H NMR spectroscopy and DFT calculations.;In Chapter Three, the reactions of the sterically variable aryl-substituted diethylenetriamines with CoCl2 to afford NNN-chelated complexes are reported. Notably, the analogues iron(II) complexes are not produced. The introduction of a picolyl donor affords the ligand set, N-picolyldiethylenetriamine, which is capable of coordinating to iron and cobalt in a pseudo-tetradentate fashion.;In Chapter Four, the N-aryl substituted NNN -iron(II) and -cobalt(II) complexes are activated by the addition of excess methylaluminoxane for the oligomerisation of ethylene. The activities are low-to-moderate at 1 bar ethylene pressure and the selectivity of the catalysts is dependent on the metal centre with the iron systems forming linear alpha-olefins while the cobalt systems give a mixture of linear and branched oligomers.;In Chapter Five, the versatile preparation of the novel NNO- ligand sets anisole-pyidine-imine, phenol-pyridine-imine and phenol-pyridine-amine and their coordination behaviour in aluminium(III), iron(II) and cobalt(II) complexes is described. Preliminary catalytic evaluation studies reveal moderate-to-high activities for the polymerisation of ethylene into moderate-to-high molecular weight polyethylene.