A Polarographic Investigation of the Reactions between Nitrate Ions and Chromium(II)–Cyclohexanediaminetetraacetate, Chromium(II)–Trimethylenediaminetetraacetate, and Chromium(II)–N-(2-Hydroxyethyl)ethylenediaminetriacetate Complexes

Abstract

Abstract Kinetic studies of the reactions between nitrate ions and Cr(II)–Y complexes, where Y represents cyclohexanediaminetetraacetic acid (CyDTA), trimethylenediaminetetraacetic acid (TRDTA), and N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), have been carried out. The reaction mechanisms of these complexes at the dropping mercury electrode were found to be expressed by the following equations: (Remark: Graphics omitted.) The formation constant, K, and the rate constants, k1 and k2, were determined in 0.1 M acetate buffer solutions of μ=0.5 by procedures including a curve-fitting method; the results were K=2.0×104 M−1, k1=0.55 M−1 s−1 and k2=2.8 M−1 s−1 for Cr(II)–CyDTA, K=2.4×10−5 M−1, k1=1.0×102 M−1 s−1, and k2<3 M−1 s−1 for Cr(II)–TRDTA and k1∼2×103 M−1 s−1 for Cr(II)–HEDTA.