F. J. Langmyhr, T. Stumpe
1965
Citations
0
Influential Citations
21
Citations
Journal
Analytica Chimica Acta
Abstract
Abstract The complex formation of iron(III) with the trisodium salt of 5-[α-(3-carboxy-5-methyl-4-oxo-2,5-cyclohexadien-1-ylidene)-2-sulfobenzyl]-3-methylsalicylic acid (eriochrome cyanine R) was studied by spectrophotometry. The pure tetrabasic acid of the ligand (H 4 ER) was prepared and used in the investigation. In the pH range 2.7–4.2 three complexes were detected: a ring-formed dimer Fe 2 (ER) 2 , Fe 2 (ER) and Fe(ER) ; the absolute stability constants (at an ionic strength of 0.1 M and at room temperature (20 ± 3°)) were log k = 37.9, log k = 22.5 and log k = 17.9, respectively.