THE IRON(III) AND IRON(II) COMPLEXES OF NITRILOTRIACETIC ACID
- 1 January 1994
- journal article
- research article
- Published by Taylor & Francis in Journal of Coordination Chemistry
- Vol. 31 (1) , 67-78
- https://doi.org/10.1080/00958979408022546
Abstract
Because of conflicting and incomplete reports of the ferric and ferrous nitrilotriacetate (NTA, H3L) equilibria in the literature, and uncertainties about the metal complex species present under various conditions, the system was investigated by potentiometric and spectrometric measurements, and the data were analyzed by simultaneous consideration of all species present. The new constants for the ferric complexes at 25.0°C and μ = 0.100 (KCl) are the stepwise formation constant log KML2 = 8.07, and the successive hydrolysis constants, log KM(OH)L = −4.36, log KM(OH)2L = −7.58, and log KM(OH)3L = −10.72. The first stepwise formation constant, log KML = 15.9, was not determined in the present work since the value of 15.9 was considered accurate. For the ferrous complexes under the same conditions, the constants reported are: log KML = 8.90, log KML2 = 3.08, and log KM(OH)L = −10.82. The log protonation constants of the ligand under these conditions are reported as 9.59, 2.52, and 1.47.Keywords
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