Potentiometric study of azide complexes of iron(III) in aqueous medium

Abstract

The stepwise formation of iron(III)-azide complexes in aqueous sodium perchlorate medium has been investigated at 25.0±0.1°C and ionic strength 3.0 M. By the indirect potentiometric method employed, using a glass electrode and under the conditions studied, five strong mononuclear complexes were detected. No evidence of polynuclear species was found. The final analysis of the data, by solution of simultaneous equations (matrix method), leads to the following overall formation constants: β 1 = 2.23 × 10 5 M −1, β 2 = 1.55 × 10 8 M −2, β 3 = 1.36 × 10 10 M −3, β 4 = 3.18 × 10 11 M −4 and β 5 = 3.11 × 10 12 M −5. The graphical method of Leden, with some refinements, was also utilized initially.