Metal chelates of phosphonate-containing ligands-V Stability of some 1-hydroxyethane-1,1-diphosphonic acid metal chelates.
A detailed study of the complexes formed between 1-hydroxyethane-1,1-diphosphonic acid and twelve metal ions, including the alkaline earth and transition non-transition metal ions, is reported. The formation constants of the protonated and unprotonated complexes are measured from potentiometric data and possible structural formulae are given. The results reveal that only mononuclear (1:1) di-, mono- and unprotonated metal chelates are formed and that the general order of stability for the unprotonated complexes is Zn > Mn > Ca > Cu > Cd > Pd > Ni > Co reverse similar Sr > Mg > Ag > Ba.
Rizkalla
E N
EN
Department of Chemistry, Ain Shams University, Cairo, Egypt.
Zaki
M T
MT
Ismail
M I
MI