Influence of O/S/Se Exchange on the Stability of 1,3,4-Selana(Thia/Oxa)Diazole-Palladium Complexes as Studied by Electrospray Ionization Mass Spectrometry

Abstract

The complexes of 2-phenyl-1,3,4-selena(thia/oxa)diazole with a palladium cation were studied by using electrospray ionization mass spectrometry. Palladium chloride was used as a source of palladium cations. The complexes of ligand:metal stoichiometry of 3:1 (ions L₃+PdCl]⁺) were formed for selenadiazoles and thiadiazoles. Quantum mechanical calculations performed indicated that ligand molecules are attached to palladium cation by the N-4 atom. The fragment ions formed L₂–H+Pd]⁺ may be regarded as organometallic species. Selenadiazoles were found more prone to form the palladium complexes than thiadiazoles. Oxadiazoles did not yield the respective palladium complexes. For comparison, the nickel cation was also included in the study but only 1:1, and less abundant 2:1 complexes were observed. Exchange of selenium into oxygen does not affect the abilities of the ligands to form nickel complexes.