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Platinum(II) and palladium(II) complexes are well-known to catalyze the partial oxidation of alkanes. Herein, we present experimental evidence that tunneling occurs in the protonolysis of M(II)-CH(3) (M = Pt, Pd) model systems. We propose that there may be a connection between the observation of tunneling and a protonolysis mechanism involving direct protonation of the M-C bond and that tunneling may also be expected for electrophilic C-H activation of methane by Pt(II) and Pd(II) that proceeds via direct proton loss from a sigma complex.
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http://dx.doi.org/10.1021/ja807427d | DOI Listing |
Chemistry
October 2021
Department of Chemistry, Reed College, 3203 SE Woodstock Blvd., Portland, OR 97222.
The kinetic isotope effect (KIE) is key to understanding reaction mechanisms in many areas of chemistry and chemical biology, including organometallic chemistry. This ratio of rate constants, k /k , typically falls between 1-7. However, KIEs up to 105 have been reported, and can even be so large that reactivity with deuterium is unobserved.
View Article and Find Full Text PDFInorg Chem
October 2016
Department of Applied Chemistry and Institute of Natural Sciences, Kyung Hee University, 1 Seochun-Dong, Giheung-Gu, Yongin-Si, Gyeonggi-Do 446-701, Korea.
Protonolysis by platinum or palladium complexes has been extensively studied because it is the microscopic reverse of the C-H bond activation reaction. The protonolysis of (COD)PtMe, which exhibits abnormally large kinetic isotope effects (KIEs), is proposed to occur via a concerted pathway (S2 mechanism) with large tunneling. However, further investigation of KIEs for the protonolysis of ZnMe and others led to a conclusion that there is no noticeable correlation between the mechanism and magnitude of KIE.
View Article and Find Full Text PDFJ Am Chem Soc
December 2008
Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, USA.
Platinum(II) and palladium(II) complexes are well-known to catalyze the partial oxidation of alkanes. Herein, we present experimental evidence that tunneling occurs in the protonolysis of M(II)-CH(3) (M = Pt, Pd) model systems. We propose that there may be a connection between the observation of tunneling and a protonolysis mechanism involving direct protonation of the M-C bond and that tunneling may also be expected for electrophilic C-H activation of methane by Pt(II) and Pd(II) that proceeds via direct proton loss from a sigma complex.
View Article and Find Full Text PDF