Synthesis and Characterization of Zn(II) and Cd(II) Complexes with Bisdithiophosphonates

2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiodiphosphetane-2,4-disulfide (Lawesson’s reagent) reacts with stoichiometric equivalent of alkane diols HO(CH2)nOH (n=2, 3, and 5) to form bisdithiophosphonic acid. The obtained crude bisdithiophosphonic acids are treated with dry NH3 to give ammonium salts of bisdithiophosphonic acids. Ammonium salts of bisdithiophosphonic acids react with ZnSO4 in water and Cd(Ac)2 in ethanol to form new bisdithiophosphonate complexes of Zn(II) and Cd(II). The zinc and cadmium complexes of these tetradentate ligands are isolated in high yields. Ammonium salts of bisdithiophosphonic acids and their Zn(II) and Cd(II) complexes are characterized by elemental analyses, mass spectra (ESI), IR and NMR spectroscopies.