Synthesis, characterization and fluxional behaviour of allylic palladium(II) carboxylate and N,N′- diarylformamidido complexes

[Pd(1-3-η-allyl)Cl]2 reacts with Li(N,N′-diarylformamidido) forming dimeric complexes of the type [Pd(1-3-η-allyl) (p-RC6H4N{A figure is presented}CH{A figure is presented}NC6H4R-p]2 (R = CH3, H, Cl). 1H NMR spectra show the presence of two conformers, one of which has two electronically equivalent allyl groups; their concentration ratio is independent of the temperature, suggesting that no intramolecular process takes place. At 80-100 °C the other conformer undergoes an intramolecular process which brings the two allyl groups to equivalence. This together with the mechanism of the process which results in the equivalence of the allyl groups in the closely related dimeric carboxylate systems, is discussed below. The presence of weak bridge-splitting ligands, such as DMSO or the parent N,N′-diarylformamidine, does not affect the intramolecular process, which thus occurs without any palladium-formamidido bond breaking, probably through a boat inversion of the C2N4Pd2 ring via a chair conformation. © 1975.