Structural characterisation of solution species implicated in the palladium-catalysed Heck reaction by Pd K-edge X-ray absorption spectroscopy: palladium acetate as a catalyst precursor

Autor:	John Evans, Thomas Neisius, Anthony R. J. Genge, Vijaya L. Kambhampati, Andrew J. Dent, Graham Rayner, Lynn O'Neill, Sandra Turin
Rok vydání:	2002
Předmět:	Crystallography X-ray absorption spectroscopy chemistry Extended X-ray absorption fine structure Heck reaction chemistry.chemical_element General Chemistry Crystal structure Carbon-13 NMR Oxidative addition Palladium Catalysis
Zdroj:	Journal of the Chemical Society, Dalton Transactions. :2207-2212
ISSN:	1364-5447 1472-7773
Popis:	Energy dispersive EXAFS (EDE), Quick EXAFS (QEXAFS), 13C NMR and X-ray crystallography have been used to probe the co-ordination sphere of palladium in the course of the phosphine free Heck reaction. [Pd2I6][NBu3H]2 has been isolated from the precatalytic solution and its crystal structure determined. EDE and QEXAFS spectra of the complexes Pd(OAc)2, Pd(PPh3)4 and [Pd2I6][NEt3H]2 illustrated the value of the technique in structure elucidation. EXAFS of the precatalytic solution detects [Pd2I6]2− and no co-ordinated carbon. EXAFS of the catalytic solution shows a first co-ordination sphere of 2 carbon atoms and a second of 2–2.5 iodines. A scheme involving an equilibrium between the oxidative addition product and the olefin co-ordination species, has been proposed to explain these results.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::c3e0df908be9ca862efb0123e2a53251 https://doi.org/10.1039/b200617k Zobrazit plný text záznamu