Determination of Property Constant of Lead Complexes with Dibromo-o-carboxy-chlorophosphonazo and Dbromo-p-p'-dimethylsulfonazo

Abstract

Two sensitive reactions between lead(II) and dibromo-o-carboxy-
chlorophosphonazo (DBKCPA) at pH 8.5 between lead(II)
and dibromo-p-p´-dimethylsulfonazo (DBMSA) at pH 9 were investigated.
The β-correction spectrophotometry was applied to the
determination of properties of Pb complex solutions instead of the
ordinary method. The multi-coordination reaction was observed in
Pb-DBKCPA reaction system. Results showed that the complex
ratio of Pb(II) to DBKCPA and to DBMSA were equal to 1 : 7 and
  1 : 2 respectively. Also, the cumulative stability constant (K) of
Pb( (DBKCPA)₇ was equal to 3.04 x 10³⁴ and that of Pb(DBMSA)₂
1.74 x 10¹⁰ and their end-step real absorptivities were as follows:
ε⁶³⁰_Pb(DBKCPA)7 = 1.10 x 10⁴ L mol^–1 cm^–1 and ε⁶⁵⁰_Pb(DBMSA)3 = 3.37 x 10⁴ L mol^–1 cm^–1 respectively.