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|Titolo:||Insertion of Isocyanides across the Pd−C Bond of Phosphinoquinoline Allyl Palladium Complexes Bearing η1 - and η3 ‑Coordinated Allyl Groups. A Synthetic and Mechanistic Study|
|Autori interni:||BERTOLASI, Valerio|
|Data di pubblicazione:||2014|
|Abstract:||BSTRACT: We undertook an exhaustive study on the structural haracteristics and reactivity toward the insertion of isocyanides cross the Pd−C bond of palladium complexes bearing coordinated hloride, bidentate phosphoquinolines as spectator ligands, and iﬀerently substituted allyl groups. It was shown that the allyl apticity is inﬂuenced not only by the nature of the spectator ligand ut also by the position of the methyl substituents on the allyl agment. Thus, in the presence of chloride, the κ1 -η3 conﬁguration is ways assumed when the distorted 8-(diphenylphosphino)-2-methyl uinoline (DPPQ-Me) acts as ancillary ligand, whereas the nsubstituted 8-(diphenylphosphino)quinoline ligand (DPPQ) gen- rally favors the κ2 -η1 conﬁguration with the exception of the complex with the 2-methyl-substituted allyl fragment, which adopts the κ2 -η3 conﬁguration with chloride as the counterion. We have etermined the reactivity toward the insertion of the isocyanide on the Pd−C bond, and we have observed decidedly diﬀerent ate laws when η3 -or η1 -allyl complexes were investigated. In particular, the rate law of the reaction involving the η1 -allyl erivatives displays a second-order dependence on complex and isocyanide concentration, whereas the insertion on η3 -allyl omplexes is better described by a ﬁrst-order process. We have interpreted such experimental results on the basis of a general pre- quilibrium mechanism in which the observed rates of the studied reactions are governed by the magnitude of the equilibrium onstant. Finally, we have determined the solid-state structure of the insertion product palladium(chloro)(8- diphenylphosphino)quinoline)(2,6-dimethyl-N-(4-methylpent-3-enylidene)benzenamine) (complex 1Bd).|
|Appare nelle tipologie:||03.1 Articolo su rivista|
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