Fluxional behaviour of allylpalladium(II) derivatives of N,N′-diarylformamidines and 1,3-diaryltriazenes

Abstract

Reactions of allylpalladiumchloride dimer with neutral ligands (L = RNCHNHR, R = C 6H 5CH 2, p-CH 3C 6H 4, p-ClC 6H 4; L = RNNNHR, R = p-CH 3C 6H 4, p-ClC 6,H 4) afford bridge splitting products of the type PdClL(1,3-η-C 3H 5). Variable temperature 1H and 13C NMR spectra show two dynamic processes in solution. The first one, operating at room temperature, involves the dissociation of the neutral ligand L; the second one, which has a lower activation energy, is concentration dependent and involves chloride-L exchange, probably via a pentacoordinated chloro bridged species. The influence of the basicity of the ligands on the activation energies of the processes is discusseed.