Mono(imino)pyridine ligands with differing imino carbon substituents have been synthesized and characterized via NMR spectroscopy and computational analysis.  Our data suggests that E and Z isomeric forms of the imines are viable, with imino carbon substituents of limited steric bulk (such as methyl) favoring the E isomer, substituents of great steric bulk (such as tert-butyl) favoring the Z isomer, and substituents of intermediate steric bulk (such as phenyl or isopropyl) favoring equilibrium mixtures of both isomeric forms.  Complexation of these ligands with NiBr2(DME) has been achieved, and select X-ray crystal structures reveal dimeric Ni(II) complexes with distorted trigonal bipyramidal geometry about nickel.  Preliminary results indicate these complexes are precatalysts for ethylene oligomerization.  Currently, we are probing the utility of sterically hindered imino carbon substituents as a catalyst design feature for improved polymer molecular weight control.

Structural analysis of mono(imino)pyridine ligands for Ni(II): Precatalysts for the oligomerization of ethylene

246th National Meeting (2013)

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