Equilibrium studies on the formation of nitrite complexes of the divalent d¹⁰ acceptors

The results of equilibria studies on the step-wise formation of complexes in an aqueous solution of unit ionic strength between sodium nitrite and Zn(II), Cd(II) and HG(II) perchlorates are reported. The formation constants have been determined potentiometrically at 298K. Mononuclear complexes are formed in all cases. Values of the overall constants for the formation of Zn(NO₂)⁺, Zn(NO₂)₂, Cd(NO₂)⁺, Cd(NO₂)₂, Hg(NO₂)⁺, Hg(NO₂)₂, Hg(NO₂)₃^- and Hg(NO₂)₄^2- are found to be 2.37±0.03 M^-1, 3.1±0.1 M^-2; 35±1 M^-1 (6.8±0.1) x 10² M^-2; (8.76±0.15) x 10⁵ M^-1 (8.22±0.09) x 10⁹ M^-2 (2.85±0.02) x 10¹¹ M^-3 and (7.31±0.03) x 10¹¹ M^-4 respectively.