Ess, Daniel H. and Bischof, Steven M. and Oxgaard, Jonas and Periana, Roy A. and Goddard, William A., III (2008) Transition state energy decomposition study of acetate-assisted and internal electrophilic substitution C−H bond activation by (acac-O,O)_2Ir(X) complexes (X = CH_3COO, OH). Organometallics, 27 (24). pp. 6440-6445. ISSN 0276-7333 http://resolver.caltech.edu/CaltechAUTHORS:20090512-100240806
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Chelate-assisted and internal electrophilic substitution type transition states were studied using a DFT-based energy decomposition method. Interaction energies for benzene and methane C−H bond activation by (acac-O,O)_2Ir(X) complexes (X = CH_3COO and OH) were evaluated using the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA). A ratio of ~1.5:1 for forward to reverse charge-transfer between (acac-O,O)_2Ir(X) and benzene or methane transition state fragments confirms “ambiphilic” bonding, the result of an interplay between the electrophilic iridium center and the internal base component. This analysis also revealed that polarization effects account for a significant amount of transition state stabilization. The energy penalty to deform reactants into their transition state geometry, distortion energy, was also used to understand the large activation energy difference between six-membered and four-membered acetate-assisted transition states and help explain why these complexes do not activate the methane C−H bond.
|Additional Information:||© 2008 American Chemical Society. Received July 10, 2008. Publication Date (Web): November 13, 2008. This research was partially supported with funding from Chevron Corporation. The computer systems used were provided by ARO-DURIP and ONR-DURIP. D.H.E. thanks Rustam Khaliullin for help using the ALMO-EDA method. Supporting Information Available: Cartesian Coordinates, absolute energies, and full Q-Chem 126.96.36.199 reference. This material is available free of charge via the Internet at http://pubs.acs.org.OM8006568.|
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|Deposited By:||Tony Diaz|
|Deposited On:||14 Aug 2009 17:13|
|Last Modified:||26 Dec 2012 11:00|
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