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Dipalladium(I) Terphenyl Diphosphine Complexes as Models for Two-Site Adsorption and Activation of Organic Molecules

Lin, Sibo and Herbert, David E. and Velian, Alexandra and Day, Michael W. and Agapie, Theodor (2013) Dipalladium(I) Terphenyl Diphosphine Complexes as Models for Two-Site Adsorption and Activation of Organic Molecules. Journal of the American Chemical Society, 135 (42). pp. 15830-15840. ISSN 0002-7863. PMCID PMC3851319. http://resolver.caltech.edu/CaltechAUTHORS:20131206-095913163

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Abstract

A para-terphenyl diphosphine was employed to support a dipalladium(I) moiety. Unlike previously reported dipalladium(I) species, the present system provides a single molecular hemisphere for binding of ligands across two metal centers, enabling the characterization and comparison of the binding of a wide variety of saturated and unsaturated organic molecules. The dipalladium(I) terphenyl diphosphine toluene-capped complex was synthesized from a dipalladium(I) hexaacetonitrile precursor in the presence of toluene. The palladium centers display interactions with the π-systems of the central ring of the terphenyl unit and that of the toluene. Exchange of toluene for anisole, 1,3-butadiene, 1,3-cyclohexadiene, thiophenes, pyrroles, or furans resulted in well-defined π-bound complexes which were studied by crystallography, nuclear magnetic resonance (NMR) spectroscopy, and density functional theory. Structural characterization shows that the interactions of the dipalladium unit with the central arene of the diphosphine does not vary significantly in this series allowing for a systematic comparison of the binding of the incoming ligands to the dipalladium moiety. Several of the complexes exhibit rare μ–η^2:η^2 or μ–η^2:η^1(O or S) bridging motifs. Hydrogenation of the thiophene and benzothiophene adducts was demonstrated to proceed at room temperature. The relative binding strength of the neutral ligands was determined by competition experiments monitored by NMR spectroscopy. The relative equilibrium constants for ligand substitution span over 13 orders of magnitude. This represents the most comprehensive analysis to date of the relative binding of heterocycles and unsaturated ligands to bimetallic sites. Binding interactions were computationally studied with electrostatic potentials and molecular orbital analysis. Anionic ligands were also demonstrated to form π-bound complexes.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ja406696k DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja406696kPublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3851319/PubMed CentralArticle
ORCID:
AuthorORCID
Agapie, Theodor0000-0002-9692-7614
Additional Information:© 2013 American Chemical Society. Received: July 1, 2013. Publication Date (Web): September 25, 2013. We thank Aaron Sattler for helpful discussion and Lawrence M. Henling and Jens Kaiser for assistance with collection of crystallographic data. We are grateful to Caltech, BP, NSF CAREER CHE-1151918, and NSF GRFP (S.L.) for funding. We thank the Gordon and Betty Moore Foundation for their generous support of the Molecular Observatory at Caltech. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU Award to Caltech (Grant No. CHE-0639094). The 400 MHz NMR spectrometer was purchased via an NIH award (No. RR027690). The authors declare no competing financial interest
Funders:
Funding AgencyGrant Number
NSF CHE-1151918
NSF Graduate Research FellowshipUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
NSFCHE-0639094
NIHRR027690
CaltechUNSPECIFIED
BPUNSPECIFIED
PubMed Central ID:PMC3851319
Record Number:CaltechAUTHORS:20131206-095913163
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20131206-095913163
Official Citation:Dipalladium(I) Terphenyl Diphosphine Complexes as Models for Two-Site Adsorption and Activation of Organic Molecules Sibo Lin, David E. Herbert, Alexandra Velian, Michael W. Day, and Theodor Agapie Journal of the American Chemical Society 2013 135 (42), 15830-15840
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42883
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Dec 2013 18:41
Last Modified:05 May 2017 20:47

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