Issue 8, 2020

Discovery and mechanistic investigation of Pt-catalyzed oxidative homocoupling of benzene with PhI(OAc)2

Abstract

We present a Pt-catalyzed direct coupling of benzene to biphenyl. This catalytic reaction employs a cyclometalated platinum(II) complex [PtMe(bhq)(SMe2)] (bhq = benzo[h]quinolate) with PhI(OAc)2 as an oxidant and does not require an acid, a co-catalyst or a solvent. The reaction kinetics and characterization of potential catalytic species are reported. The reaction is first-order in Pt and second-order in benzene, which implicates the second C–H activation step as rate-determining. A Pt(II)/Pt(IV) catalytic cycle is suggested. The reaction commences by oxidation of the Pt(II) complex to give the platinum(IV) species [Pt(bhq)(SMe2)(OAc)2](OAc) followed by C–H activation of benzene to afford the intermediate [PtPh(bhq)(SMe2)(OAc)](OAc) concurrently with the release of HOAc. A second benzene molecule reacts similarly to give the diphenyl intermediate [PtPh2(bhq)(SMe2)](OAc). C–C bond forming reductive elimination ensues to regenerate Pt(II) and complete the catalytic cycle. The proposed mechanism has been examined by DFT computations, which provide support to experimental findings.

Graphical abstract: Discovery and mechanistic investigation of Pt-catalyzed oxidative homocoupling of benzene with PhI(OAc)2

Supplementary files

Article information

Article type
Paper
Submitted
04 nóv. 2019
Accepted
15 jan. 2020
First published
15 jan. 2020

Dalton Trans., 2020,49, 2477-2486

Author version available

Discovery and mechanistic investigation of Pt-catalyzed oxidative homocoupling of benzene with PhI(OAc)2

S. M. Nabavizadeh, F. Niroomand Hosseini, C. Park, G. Wu and M. M. Abu-Omar, Dalton Trans., 2020, 49, 2477 DOI: 10.1039/C9DT04261J

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