Mechanistic aspects of hydrocarbon C-H bond oxygenation with platinum complexes: Substrate selectivity for the Shilov system and its models

ORGN 429

John E. Bercaw, Jay A. Labinger, jal@its.caltech.edu, Jon S. Owen, jowen@caltech.edu, Tom G. Driver, and George Chen. Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, CA 91125
Organometallic reagents offer potentially attractive selectivity for partial oxidation of methane and other substrates, including its primary oxidation products with dioxygen, and among organometallic reagents that activate carbon-hydrogen bonds, the "Shilov System", stoichiometric oxidation of alkanes to alcohols by aqueous Pt(IV), exhibits unusual selectivity and better compatibility with oxidants and protic reagents. Using a variety of kinetics, isotopic labeling and stereochemical studies, we have examined the mechanisms of the individual steps of the Shilov cycle. The rate and selectivity determining step of the cycle is the initial coordination of the C-H bond to Pt(II). A series of bis(aryl)diimine-ligated Pt(II) methyl cations are found to provide better characterized models for the reactive species in the Shilov System. These react smoothly in trifluoroethanol solvent with the C-H bonds of arenes, alkanes, methanol and dimethylether, and the relative rates for these models reactions have been measured.
 

George A. Olah Award in Hydrocarbon or Petroleum Chemistry
8:10 AM-12:00 PM, Wednesday, 29 March 2006 Georgia World Congress Center -- Georgia Ballroom 2, Oral

Division of Organic Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006