REACTION BETWEEN [PDCL4](2-) AND 5,5-DIMETHYL-2-THIOXOIMIDAZOLIDIN-4-ONE

The reaction between 5,5-dimethyl-2-thioxoimidazolidin-4-one (H(2)L) a nd [PdCl4](2-) has been studied in aqueous solution by potentiometric and spectrophotometric measurements. In the presence of the palladium salt, H(2)L is completely monodeprotonated (HL(-)); from spectrophotom etric measurements, only two complexes having 1:1 and 1:2 Pd/ligand mo l ratios have been identified. Potentiometric titrations, carried out on solutions with 1:1, 1:2, 1:3 and 1:4 metal/ligand mol ratios, show that these complexes must be formulated as Pd(HL)(2) and [Pd-2(HL)(2)( mu H2O)(mu-OH)](+). Ionization constants of the pure ligand and format ion constants of the complexes give pH distribution curves of the vari ous species and the spectra of the two complexes. From MeOH, S-coordin ated Pd(H(2)L)(n)Cl-2 (n = 2-4) complexes have been separated in the s olid state; from water, two complexes of formula Pd(H(2)L)(HL)Cl and P d(HL)Cl have been obtained with HL(-) N,S-coordinated to the metal.