DECOMPOSITION INTERMEDIATES IN PALLADIUM-DITHIOESTER SYSTEMS

Palladium dihalides react with the ligands EtO(2)CCH(2)(CH3)NCS(3)R (R = Me, ESDTM; R = Et, ESDTE) in non-polar solvents yielding the trans-[Pd(ESDTR)(2)X(2)] (X = Cl, Br or I) complexes in which the dithioester molecule coordinates through thiocarbonyl sulphur. Thermal degradation of these complexes has been investigated up to 1000 degrees C. The first decomposition step involves evolution of one alkyl halide molecule to form the [Pd(ESDT)(ESDTR)X] (X = Cl or Br) intermediates. At higher temperature S-dealkylation of the neutral ligand takes place with consequent formation of [Pd(ESDT)(2)] as a second intermediate. The mixed species [Pd(ESDT) (ESDTR)X] have been also prepared by reaction of [Pd(ESDT)X], with the appropriate dithioester, as for the [Pd(ESDT)(DMDTM)X] (X = Cl or Br; DMDTM = MeS(2)CNMe(2)) analogues. The complexes have been characterized by elemental analyses and IR and H-1 NMR spectroscopy. The behaviour of the 1.2 adducts and of the related mixed species in solution is described on the basis of proton NMR spectra.