Structural Characterization of β-Agostic Bonds in Pd-Catalyzed Polymerization

Hongwei Xu, Chunhua Tony Hu, Xiaoping Wang, Tianning Diao

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

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 languageEnglish
Pages (from-to)4099-4102
Number of pages4
JournalOrganometallics
Volume36
Issue number21
DOIs
StatePublished - 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.

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