Spectrophotometric Study of the Complex Equilibria in Palladium-Chromeazurol S System

Department of Chemistry, University of Allahabad, Allahabad Manuscript received 10 March 1970; accepted for publication 9 February 1972 The complex formation between palladium (II)and trisodium salt of 3"-sulpho-2" :66 -dichloro-3: 3'-dimethyl-4-hydroxyfuchsone-5 : 5'-dicarboxylic acid (Chromeazurol S; abbr. CAS) has been studied spectrophotometrically. The formation of 2: 1, 2 : 2 and 1 : 1 (metal: ligand) complexes has been inferred by analysing the spectral data, using Asmus's straight line and the continuous variation method. The stability constants of the chelates (ionic strength 0.1M NaNO3 ; temperature 25°) are log K( 2,1) pH3.5= 9.80, log K(2,2) pH3.8= 15.27 and log K(1,1)p H4.5= 4.91.