Abstract The phosphorus analogue of EDTA was prepared by alkylation of Cl 2 PCH 2 CH 2 PCl 2 with ethyl bromozincacetate and hydrolysis of the ester formed. It was isolated as crystalline tetrasodium salt monohydrate,(NaOOCCH 2) 2 PCH 2 CH 2 P (CH 2 CoONa) 2. H 2 O, stable on air and well soluble in water. The free acid was only obtained in solution. The structure of the new ligand was checked by spectral methods (UV, IR, and 1 H, 13 C and ...