Copolymerization of ethylene with linear α-olefins by 2-phosphinophenolate nickel catalysts

2‐Dicyclohexyl‐ and 2‐diphenylphosphinophenol, CCHH and PPHH, react with Ni(1,5‐COD)2 to form catalysts for polymerization of ethylene in or copolymerization with α‐olefins. The more P‐basic CCHH/Ni catalyst allows concentration‐dependent incorporation of olefins to give copolymers with isolated side groups and higher molecular weights, whereas the PPHH/Ni catalyst undergoes mainly stabilizing interactions with the olefins and leads to ethylene oligomers with no or marginal olefin incorporation. Pressure–time plots of the batch reactions show that the ethylene conversion is usually slower by catalysis with CCHH/Ni than by PPHH/Ni. The microstructure of the copolymers was determined by 13C NMR spectra, the number of side groups per main chain was estimated by 1H NMR analyses. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 258–266, 2009 2‐Dicyclohexyl‐ and 2‐diphenylphosphinophenol, CCHH and PPHH, react with Ni(1,5‐COD)2 to form catalysts for polymerization of ethylene in or copolymerization with α‐olefins. The more P‐basic CCHH/Ni catalyst allows concentration‐dependent incorporation of olefins to give copolymers with isolated side groups, whereas the PPHH/Ni catalyst undergoes only stabilizing interactions with most olefins and leads to oligomers with no or marginal olefin incorporation.