Intramolecular C−H Activation of a Bisphenolate(benzene)-Ligated
Titanium Dibenzyl Complex. Competing Pathways Involving α-Hydrogen
Abstraction and σ-Bond Metathesis
Suzanne
R. Golisz
Jay A. Labinger
John E. Bercaw
10.1021/om100253u.s002
https://acs.figshare.com/articles/journal_contribution/Intramolecular_C_H_Activation_of_a_Bisphenolate_benzene_Ligated_Titanium_Dibenzyl_Complex_Competing_Pathways_Involving_Hydrogen_Abstraction_and_Bond_Metathesis/2715151
A titanium dibenzyl complex featuring a ligand with two phenolates
linked by a benzene-1,3-diyl group was found to undergo thermal decomposition
to give toluene and a cyclometalated dimeric complex. The thermal
decomposition followed first-order kinetics and was studied at a number
of temperatures to determine the activation parameters (Δ<i><i>H</i></i><sup><i></i></sup><sup>⧧</sup>= 27.2(5) kcal/mol and Δ<i><i>S</i></i><sup><i></i></sup><sup>⧧</sup> = −6.2(14)
cal/(mol K)). Deuterated isotopologues were synthesized to measure
the kinetic isotope effects. The complexes with deuterium in the benzyl
methylene positions decomposed more slowly than the protio analogues.
Isotopologues of toluene with multiple deuteration positions were
observed in the product mixtures. These data are consistent with competing
α-abstraction and σ-bond metathesis.
2010-11-08 00:00:00
benzene
Complex
MetathesisA
phenolate
kinetic
Pathway
Bisphenolate
metathesi
Abstraction
ligand
product mixtures
Activation
complex
decomposition
isotopologue
toluene
isotope effects
protio analogues
deuterium
cyclometalated dimeric
activation
Dibenzyl
parameter
data
Bond
Deuterated
abstraction
Intramolecular
benzyl methylene positions
cal
dibenzyl
deuteration positions
kcal
Isotopologue
bond