C–H and O ₂ Activation at a Pt(II) Center Enabled by a Novel Sulfonated CNN Pincer Ligand

Journal Article · Wed Sep 21 00:00:00 EDT 2016 · Organometallics

DOI:https://doi.org/10.1021/acs.organomet.6b00613· OSTI ID:1325840

Watts, David ^[1]; Wang, Daoyong ^[1]; Adelberg, Mackenzie ^[1]; Zavalij, Peter Y. ^[1]; Vedernikov, Andrei N. ^[1]

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1. Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States

A novel sulfonated CNN pincer ligand has been designed to support CH and O₂ activation at a Pt(II) center. The derived cycloplatinated aqua complex 7 was found to be one of the most active reported homogeneous Pt catalysts for H/D exchange between studied arenes (benzene, benzene-d₆, toluene-d₈, p-xylene, and mesitylene) and 2,2,2-trifluoroethanol (TFE) or 2,2,2-trifluoroethanol-d; the TON for C₆D₆ as a substrate is >250 after 48 h at 80 °C. The reaction is very selective; no benzylic CH bond activation was observed. The per-CH-bond reactivity diminishes in the series benzene (19) > toluene (p-CH:m-CH:o-CH = 1:0.9:0.2) > xylene (2.9) > mesitylene (1.1). The complex 7 reacts slowly in TFE solutions under ambient light but not in the dark with O₂ to selectively produce a Pt(IV) trifluoroethoxo derivative. The H/D exchange reaction kinetics and results of the DFT study suggest that complex 7, and not its TFE derivatives, is the major species responsible for the arene CH bond activation. Lastly, the reaction deuterium kinetic isotope effect, k_H/k_D = 1.7, the reaction selectivity, and reaction kinetics modeling suggest that the CH bond cleavage step is rate-determining.

• Research Organization: Univ. of Maryland, College Park, MD (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Catalytic Hydrocarbon Functionalization (CCHF)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0001298
• OSTI ID: 1325840
• Alternate ID(s): OSTI ID: 1339955
• Journal Information: Organometallics, Journal Name: Organometallics Vol. 36 Journal Issue: 1; ISSN 0276-7333
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY