To increase the structural diversity
of dinucleating platforms
that are used in the construction of olefin polymerization catalysts,
we are exploring new ligand designs that feature non-alkoxide/phenoxide
bridging groups. In the current study, we demonstrate that 1,2,3-triazole-4-carboxamidate
donors are excellent <i>N</i>,<i>N</i>-chelators
for nickel and can readily bind secondary metal ions. We found that
sterically bulky nickel triazolecarboxamidate complexes are active
as ethylene homopolymerization catalysts and can afford low molecular
weight polyethylene with about 80–130 branches per 1000 carbon
atoms. The addition of zinc salts to our nickel complexes led to catalyst
inhibition in some cases, which we have attributed to the formation
of catalytically inactive mixed-metal species. To circumvent this
problem, we anticipate that further elaboration of the triazolecarboxamidate
ligand could provide discrete heterobimetallic complexes that will
be useful as single-site catalysts with unique reactivity patterns
