TY - JOUR
T1 - Transition state for intramolecular C-H bond cleavage in [(LCu)2(μ-O)2]2+ (L = 1,4,7-tribenzyl-1,4,7-triazacyclononane)
AU - Cramer, Christopher J.
AU - Pak, Youngshang
PY - 2001/5/1
Y1 - 2001/5/1
N2 - Hybrid quantum mechanical/molecular mechanical electronic structure calculations reveal the transition state for C-H bond cleavage in [(LCu)2 (μ-O)2]2+ (L=1,4,7-tribenzyl-1,4,7-triazacyclononane) to be consistent with a hydrogen-atom-transfer mechanism from carbon to oxygen. At the MPW1K/double-zeta effective core potential( + ) univeral force field level, 0 K activation enthalpies for the parent, p-CF3, and p-OH substituted benzyl systems are predicted to be 8.8, 9.5, and 7.8 kcal/mol. Using a one-dimensional Eckart potential to estimate quantum effects on the reaction coordinate, reaction in the unsubstituted system is predicted to proceed with a primary kinetic isotope effect of 22 at 233 K. Structural parameters associated with the hydrogen-atom transfer are consistent with the Hammond postulate.
AB - Hybrid quantum mechanical/molecular mechanical electronic structure calculations reveal the transition state for C-H bond cleavage in [(LCu)2 (μ-O)2]2+ (L=1,4,7-tribenzyl-1,4,7-triazacyclononane) to be consistent with a hydrogen-atom-transfer mechanism from carbon to oxygen. At the MPW1K/double-zeta effective core potential( + ) univeral force field level, 0 K activation enthalpies for the parent, p-CF3, and p-OH substituted benzyl systems are predicted to be 8.8, 9.5, and 7.8 kcal/mol. Using a one-dimensional Eckart potential to estimate quantum effects on the reaction coordinate, reaction in the unsubstituted system is predicted to proceed with a primary kinetic isotope effect of 22 at 233 K. Structural parameters associated with the hydrogen-atom transfer are consistent with the Hammond postulate.
KW - Binuclear copper
KW - C-H activation
KW - Hydrogen-atom transfer
KW - Oxygen activation
KW - Tunneling
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U2 - 10.1007/s002140000238
DO - 10.1007/s002140000238
M3 - Article
AN - SCOPUS:0035644356
SN - 1432-881X
VL - 105
SP - 477
EP - 480
JO - Theoretical Chemistry Accounts
JF - Theoretical Chemistry Accounts
IS - 6
ER -