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Title: C–H and O2 activation at a Pt(II) center enabled by a novel sulfonated CNN pincer ligand

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, kH/kD = 1.7, the reaction selectivity, and reaction kinetics modeling suggest that the CH bond cleavage step is rate-determining.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Univ. of Maryland, College Park, MD (United States)
Publication Date:
OSTI Identifier:
1325840
Grant/Contract Number:
SC0001298
Type:
Published Article
Journal Name:
Organometallics
Additional Journal Information:
Journal Volume: 36; Journal Issue: 1; Journal ID: ISSN 0276-7333
Publisher:
American Chemical Society
Research Org:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY