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- Title
Stability and Unimolecular Reactivity of Palladate(II) Complexes [L<sub> n</sub>PdR<sub>3</sub>]<sup>−</sup> (L=Phosphine, R=Organyl, n=0 and 1).
- Authors
Kolter, Marlene; Koszinowski, Konrad
- Abstract
The reduction of PdII precatalysts to catalytically active Pd0 species is a key step in many palladium-mediated cross-coupling reactions. Besides phosphines, the stoichiometrically used organometallic reagents can afford this reduction, but do so in a poorly understood way. To elucidate the mechanism of this reaction, we have treated solutions of Pd(OAc)2 and a phosphine ligand L in tetrahydrofuran with RMgCl (R=Ph, Bn, Bu) as well as other organometallic reagents. Analysis of these model systems by electrospray- ionization mass spectrometry found palladate(II) complexes [L nPdR3]− ( n=0 and 1), thus pointing to the occurrence of transmetallation reactions. Upon gas-phase fragmentation, the [L nPdR3]− anions preferentially underwent a reductive elimination to yield Pd0 species. The sequence of the transmetallation and reductive elimination, thus, constitutes a feasible mechanism for the reduction of the Pd(OAc)2 precatalyst. Other species of interest observed include the PdIV complex [PdBn5]−, which did not fragment via a reductive elimination but lost BnH instead.
- Subjects
PALLADIUM catalysts; COUPLING reactions (Chemistry); PHOSPHINE; ORGANYL groups; REACTIVITY (Chemistry); GAS phase reactions; MASS spectrometry
- Publication
Chemistry - A European Journal, 2016, Vol 22, Issue 44, p15744
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201603431