The exchange of cyclopalladated ligands in chloro-bridged palladium(II) complexes

Cyclometalation Using d-Block Transition Metals: Fundamental Aspects and Recent Trends

“…The reaction is under thermodynamic control and similar equilibria are reached in transcyclometalations using benzylamine ligands containing NMe 2 and NEt 2 donor groups, independently which of the two ligands is cyclometalated at the outset of the reaction. 147 Moreover, transcyclometalation experiments using polydeuterated AcOH-d 4 as solvent have indicated that deuterium is incorporated also into the non-metalated ortho-position of dmba. 148 This H/D exchange suggests that cyclopalladation is an equilibrium process in acetic acid and that Pd-C bond making and breaking is reversible.…”

“…147 In addition, acid-catalyzed ligand exchange via dissociative Pd-C bond cleavage of 23 has been successfully used for synthesizing metallacycles bearing arsenic 149 or selenium as donor sites. The resulting platinum bis(aryl) complex 29 has been structurally analyzed and can thermally be transformed into the final product 27 and the neutral arene 18a, probably mediated by acidolysis of the Pt-C bond of the monodentate ligand.…”

A Theoretical Assessment of the Thermodynamic Preferences in the Cyclopalladation of Amines

“…[33] As for the tertiary benzylamines, Cope and Friedrich [8] metalated the 4-methoxy and 3,5-dimethoxy derivatives, with yields very similar to the unsubstituted tertiary amine, but were unsuccessful with the 4-NO 2 analog; this compound needs stronger palladating agents, such as palladium() acetate. [34] Kinetic measurements for the cyclometallation reaction of substituted N,Ndimethylbenzylamines [9a] or N-benzyltriamines [9d] show that there is a linear correlation between the logarithm of the rate constant and the Hammett parameter, σ m , of the substituents, thus confirming that the reaction takes place through an electrophilic attack of the Pd II center on the carbon atom.…”

Synthesis of Stable Diarylpalladium(II) Complexes: Detailed Study of the Aryl–Aryl Bond‐Forming Reductive Elimination

“…The reversibility of CÀHp alladation under acidic conditions is well-documented. [14] Thus, the formation of the non-symmetrical cyclization products 6 can be rationalizedb yasequence of proto-demetalation, isomerization to the k 3 -diarylpalladium(II) complex 8,a nd reductive elimination (Scheme 2). Twof actorsm ay dictatet he selectivity of this elimination pathway.F irst, reductive elimination from 2 forms ah ighly strained product and requires high activation energies,a ss hown in the thermally induced reductive elimination ( Table 2, entries 1a nd 2).…”