Campus Units

Chemistry

Document Type

Article

Publication Version

Published Version

Publication Date

2012

Journal or Book Title

Organometallics

Volume

31

Issue

15

First Page

5586

Last Page

5590

DOI

10.1021/om3005433

Abstract

C–H insertion reactions between different substrates and diazo reagents were catalyzed by tetratolylporphyrinato methyliridium (Ir(TTP)CH3). The highest yields were achieved for reactions between the bulky diazo reagent methyl 2-phenyldiazoacetate (MPDA) and substrates containing electron-rich C–H bonds. An intermediate metalloporphyrin complex was identified as a metal–carbene complex, Ir(TTP)(═C[Ph]CO2CH3)(CH3) (4), using 1H NMR and UV/vis absorption spectroscopy. The presence of 4 was further supported by computationally modeling the absorption spectra with time-dependent DFT (6-31G(d,p)/SBKJC basis set, PBE0 functional). Kinetic studies for C–H insertion reactions using different substrates showed substantial differences in the rate of MPDA consumption, suggesting that carbene transfer is rate-limiting. Furthermore, primary kinetic isotope effects of 3.7 ± 0.3 and 2.7 ± 0.4 were measured using toluene and cyclohexane, respectively. These data are consistent with a mechanism that involves direct C–H insertion rather than a radical rebound pathway.

Comments

Reprinted (adapted) with permission from Organometallics, 2012, 31 (15), pp 5586–5590. Copyright 2012 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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