A Study of the Complex Compounds of N-Benzenesulphonyl Glycines with Some Metal Ions: Part XVII. Rotatometry of N-N'-Dibenzenesulphonyl-1-Cystine

Inorganic Chemistry Laboratory, University College of Science, Calcutta-9

Manuscript received 22 October 1973; revised 24 April 1974; accepted 27 April 1974

The stepwise acid dissociation of the optically active ligand N-N'- dibenzenesmphonyl-1-cysthie (DBSC, RH₄ or RSSR) and its complex formation with Ca(II), Zn(II) and Cd(II) ions have been followed "Rotatoznetrically" in (1:1) aqueous-dioxan at a constant ionic strength (µ=0.50) at 30^°±0.5^°. The successive acid dissociation constants (k₂* and k₁*) of the ligand DBSC and forma­tion constant of its Cu(II) chelate Cu(RH₂) have been detrmined and the values of  k₂* , k₁* and log K are found to be 4.04±0.04, 4.68±0.04 and 3.29±0.04 respectively. The results are in good agreement with those obtained potentiometricaby under identical conditions. The formation constants of Zn(II) and Cd(II) chelates of DBSC could not be evaluated due to the commencement of precipitation at the early stages of complex formation. Molar rotation [M]\(_{D}^{30}\) values of various active species such as RH₄, RH^-₃, R.H₂2^- and Cu(RH₂) have been evaluated and are found to be —445.1, —655.2, —811.2 and +241.3 degree mole^-1 under the experimental conditions.