The complexes [(PhZdtc)Pd(R,mtc)ZPd(Phzdtc)] , Pd(Rzmtc)(R;dtc)(PPhJ) and Pd(az)(Rzmtc) have been prepared (az = azobenzene-2-C,N; R = methyl,
R2 = pyrrolidyl, piperidyl and R ' = phenyl, ethyl, butyl). Infrared data reveal that in the solid state the [(Ph,dtc)Pd(R2mtc)ZPd(PhZdtc)] complexes are dimers, bridged by the suIfur atoms of the monothiocarbamate ligand. In organic solvents these complexes dissociate giving a monomer-dimer equilibrium, which is studied by 'H and 13C nmr spectroscopy. The equilibrium constants and the dissociation enthalpies were calculated from these measurements. In the monomers Pd(Rzmtc)(Ph2dtc) and in the Pd(az)(Rzmtc) complexes the thiocarbamate ligand is bidentate bonded with the palladium ion through the oxygen and the sulfur atom, whereas in the compounds Pd(R2mtc)(R2dtc)PPh3) the monothiocarbamate acts as a monodentate ligand bonded through the sulfur atom only. The activation energy and activation entropy of the hindered rotation around the C=N bond of the thiocarbamate ligand have also been determined from 'H nmr measurements. It is shown that the alkyl substituent of the thiocarbamate ligand has a much larger injluence on the values of the activation energies than the coordination mode of this ligand, i.e. whether the ligand is monodentate or bidentate bonded with the metal ion.