Abstract
β-agostic Pd complexes are critical intermediates in catalytic reactions, such as olefin polymerization and Heck reactions. Pd β-agostic complexes, however, have eluded structural characterization, due to the fact that these highly unstable molecules are difficult to isolate. Herein, we report the single-crystal X-ray and neutron diffraction characterization of β-agostic (α-diimine)Pd-ethyl intermediates in polymerization. Short Cα-Cβ distances and acute Pd-Cα-Cβ bond angles combined serve as unambiguous evidence for the β-agostic interaction. Characterization of the agostic structure and the kinetic barrier for β-H elimination offer important insight into the fundamental understanding of agostic bonds and the mechanism of polymerization.
Original language | English |
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Pages (from-to) | 4099-4102 |
Number of pages | 4 |
Journal | Organometallics |
Volume | 36 |
Issue number | 21 |
DOIs | |
State | Published - Nov 13 2017 |
Funding
H.X. is grateful to the Weck group for assistance in characterizing polyethylene. This work was supported by the National Science Foundation (CHE-1654483). The X-ray diffraction facility is partially supported by the NSF (DMR-0820341 and DMR-1420073). The CPTCI-cryoprobe was acquired through the support of the NIH (OD016343). Neutron single crystal diffraction measurements were performed at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.