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Synthetic, Structural, and Mechanistic studies on the oxidative addition of Aromatic Chlorides to a palladium (N-heterocyclic carbene) complex: Relevance to catalytic amination

journal contribution
posted on 2023-06-08, 00:45 authored by Alexandra K de K Lewis, Stephen Caddick, Geoff Cloke, Norman C Billingham, Peter B Hitchcock, John Leonard
The oxidative addition products trans-[Pd(NHC)(2)(Ar)Cl] (NHC = cyclo-C{(NBuCH)-Bu-I}(2); Ar = Me-4-C6H4, MeO-4-C6H4, CO2Me-4-C6H4) have been isolated in good yields from the reactions of ArCl with the amination precatalyst [Pd(NHC)(2)] and structurally characterized. The former undergo reversible dissociation of one NHC ligand at elevated temperatures, and a value of 25.57 kcal mol(-1) has been determined for the Pd-NHC dissociation enthalpy in the case where Ar = Me-4-C6H4. Detailed kinetic studies have established that the oxidative addition reactions proceed by a dissociative mechanism. Rate data for the oxidation addition of Me-4-C6H4Cl to [Pd(NHC)(2)] compared to that obtained for the [Pd(NHC)(2)]-catalyzed coupling of morpholine with 4-chlorotoluene are consistent with a rate-determining oxidative addition in the catalytic amination reaction. The relative rates of oxidative addition of the three aryl chlorides to [Pd(NHC)(2)] (CO2Me-4-C6H4Cl > Me-4-C6H4Cl > MeO-4-C6H4Cl) reflect the electronic nature of the substituents and also parallel observed trends in coupling efficiency for these aryl halides in aminations.

History

Publication status

  • Published

Journal

Journal of the American Chemical Society

ISSN

0002-7863

Publisher

ACS Publications

Issue

33

Volume

125

Page range

10066-10073

Department affiliated with

  • Chemistry Publications

Notes

Times Cited: 17; Keywords: HECK-TYPE REACTIONS; COUPLING REACTIONS; ARYL CHLORIDES; C-C; HALIDES; REACTIVITY; LIGANDISI:000184779100041 Other internal authors: Peter Hichcock

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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