title: Self-adaptable catalysts: substrate-dependent ligand configuration.
abstract: Pd(II) allyl and Pd(0) olefin complexes containing the configurationally labile ligand 1,2-bis-[4,5-dihydro-3H-dibenzo[c-e]azepino]ethane were studied as models for intermediates in Pd-catalyzed allylic alkylations. According to NMR and DFT studies, the ligand prefers C(s) conformation in both eta3-1,3-diphenylpropenyl and eta3-cyclohexenyl Pd(II) complexes, whereas in Pd(0) olefin complexes it adopts different conformations in complexes derived from the two types of allyl systems in both solution and, as verified by X-ray crystallography, in the solid state. These results demonstrate that the Pd complex is capable of adapting its structure to the reacting substrate. The different structural preferences also provide an explanation for the behavior of 1,3-diphenyl-2-propenyl acetate and 2-cyclohexenyl acetate in Pd-catalyzed allylic alkylations using pseudo-C2 and pseudo-C(s) symmetric ligands.
authors.affiliation: KTH School of Chemical Science and Engineering, Department of Chemistry, Organic Chemistry, SE 100 44 Stockholm, Sweden.
authors.forename: Raivis
authors.initials: R
authors.lastname: Zalubovskis
authors.forename: Alexis
authors.initials: A
authors.lastname: Bouet
authors.forename: Ester
authors.initials: E
authors.lastname: Fjellander
authors.forename: Samuel
authors.initials: S
authors.lastname: Constant
authors.forename: David
authors.initials: D
authors.lastname: Linder
authors.forename: Andreas
authors.initials: A
authors.lastname: Fischer
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lacour
authors.forename: Timofei
authors.initials: T
authors.lastname: Privalov
authors.forename: Christina
authors.initials: C
authors.lastname: Moberg