Seminar
Prof. Masashi Shiotsuki
"Mechanistic Studies of Platinum-Catalyzed
Ethylene Dimerization via Isolable
Intermediates"
August 28, 2006
Abstract:
Mechanistic studies of catalytic ethylene
dimerization with three isolable platinum complexes are
presented. Synthesis of a series of platinum intermediates
for ethylene dimerization is described, which include a
hydride ethylene complex, an ethyl ethylene complex, and
a 1-butene hydride complex. Mechanistic study shows that
the ethyl ethylene complex is the catalyst resting state
and migratory insertion is the turnover limiting step. The
barrier for this process has been determined and compared
with analogous barriers in Ni and Pd species. Low temperature
NMR study showed that rate constant of the formation of
the ethyl ethylene complex from the hydride ethylene complex
was dependent on the concentration of ethylene, which indicates
that the reaction proceeds associatively. The 1-butene hydride
complex can reacts with ethylene to reform the other active
species with the formation of 1-butene. The mechanism of
isomerization of 1-butene to internal butenes is also discussed.
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