Linked Life Data

17539029

Source:http://linkedlifedata.com/resource/pubmed/id/17539029

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
2007-8-16
pubmed:abstractText
Leaching of palladium species from Pd nanoparticles under C--C coupling conditions was observed for both Heck and Suzuki reactions by using a special membrane reactor. The membrane allows the passage of palladium atoms and ions, but not of species larger than 5 nm. Three possible mechanistic scenarios for palladium leaching were investigated with the aim of identifying the true catalytic species. Firstly, we examined whether or not palladium(0) atoms could leach from clusters under non-oxidising conditions. By using our membrane reactor, we proved that this indeed happens. We then investigated whether or not small palladium(0) clusters could in fact be the active catalytic species by analysing the reaction composition and the palladium species that diffused through the membrane. Neither TEM nor ICP analysis supported this scenario. Finally, we tested whether or not palladium(II) ions could be leached in the presence of PhI by oxidative addition and the formation of [Pd(II)ArI] complexes. Using mass spectrometry, UV-visible spectroscopy and 13C NMR spectroscopy, we observed and monitored the formation and diffusion of these complexes, which showed that the first and the third mechanistic scenarios were both possible, and were likely to occur simultaneously. Based on these findings, we maintain that palladium nanoparticles are not the true catalysts in C--C coupling reactions. Instead, catalysis is carried out by either palladium(0) atoms or palladium(II) ions that leach into solution.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0947-6539
pubmed:author
pubmed:issnType
Print
pubmed:volume
13
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6908-13
pubmed:dateRevised
2009-8-4
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Ion- and atom-leaching mechanisms from palladium nanoparticles in cross-coupling reactions.
pubmed:affiliation
Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't