A palladium-catalyzed reaction of a .pi.-allyl ligand with a nucleophile. An MO study about a feature of the reaction and a ligand effect on the reactivity

Abstract

A CNDO-type MO study was carried out for the reaction between OH-and the x-allyl ligand coordinating to palladium(ll), as a model reaction of various nucleophilic attacks on the x-allyl ligand. MO calculations showed the following feature of the reaction: when a nucleophile, Y, approaches the n-allyl ligand, the palladium(l1) is reduced to palladium(O), and the n-allyl ligand is eliminated as an allyl derivative, CHz=CHCHzY, from the palladium(0). This feature agrees with the experimental result. The reactivity regarding the OH-nucleophilic attack increases i n the order PdClz(x-C3H~)-<<

Density Functional Study on the Regioselectivity of Nucleophilic Attack in 1,3-Disubstituted (Diphosphino)(η3-allyl)palladium Cations

“…Let us now consider the nucleophilic attack at allylpalladium complexes. This process has been invoked to be determined by orbital interactions. , In all the complexes studied, the LUMO is the antibonding combination of the 7a‘ ‘ orbital of Pd(PH 3 ) 2 and of the n−π orbital of the allyl moiety (Ψ 3 in Figure ), so that the attack would take place with preference at the C1 and C3 atoms.…”

“…Theoretical calculations have been performed on (η 3 -allyl)palladium complexes dealing with diverse aspects of the complexes. The nucleophilic attack on allylpalladium complexes was first studied by Sakaki et al ., who analyzed the role of ancillary ligands by means of semiempirical CNDO calculations. Later, the same author performed theoretical calculations on geometries, bonding nature, and relative stabilities of dinuclear palladium(I) η 3 -allyl complexes and mononuclear palladium(II) η 3 -allyl complexes.…”

(N,N) vs. (N,S) chelation of palladium in asymmetric allylic substitution using bis(thiazoline) ligands: A theoretical and experimental study

“…The Pd-C bond elongation can come from a steric congestion, or, like in the case of C 1 -symmetric ligands with different donor heteroatoms, from the strong donating effect of one atom (provoking the bond elongation trans to this atom). Some theoretical studies have been done to gain a better understanding of the enantioselectivity of this reaction [18]. According to one model, an elongation of the Pd-C bond by Dl = 0.01 Å will approximately double the reactivity at this carbon [18h].…”

Effects of β-Substituents and Ancillary Ligands on the Structure and Stability of (η3-Allyl)palladium Complexes. Implications for the Regioselectivity in Nucleophilic Addition Reactions

“…7 Despite the considerable synthetic and mechanistic importance of palladium-allyl chemistry there has been a remarkable lack of high level theoretical studies published in this field. The majority of theoretical calculations on (η 3 -allyl)palladium complexes have been carried out on a semiempirical level [42][43][44][45] but very recently two ab initio studies have also appeared. The scope of these theoretical works was the investigation of the structure 45,46 and reactivity 42,43,47 of the parent, unsubstituted (η 3 -allyl)PdL 2 complex.…”

“…Despite the considerable synthetic and mechanistic importance of palladium−allyl chemistry there has been a remarkable lack of high level theoretical studies published in this field. The majority of theoretical calculations on (η 3 -allyl)palladium complexes have been carried out on a semiempirical level − but very recently two ab initio studies have also appeared. , The scope of these theoretical works was the investigation of the structure 45,46 and reactivity 42,43,47 of the parent, unsubstituted (η 3 -allyl)PdL 2 complex. However, the electronic effects induced by the functional groups and ancillary ligands on the structure and stability of the allyl−palladium complexes remained largely unstudied.…”