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Complex Formation of Alkyl-N-iminodiacetic Acids and Hard Metal Ions in Aqueous Solution and Solid State

Lindblad, Cecilia and Cassel, Anders and Persson, Ingmar (2020). Complex Formation of Alkyl-N-iminodiacetic Acids and Hard Metal Ions in Aqueous Solution and Solid State. Journal of Solution Chemistry. 49 , 1250-1266
[Research article]

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The calcium(II), iron(III) and chromium(III) alkyl-N-iminodiacetate systems have been studied in aqueous solution with respect to stability, acid-base properties and structure. The calcium(II) ion forms only one weak complex with methyl-N-iminodiacetic acid in water,K-1 = 12.9 (2) mol(-1).dm(3), while iron(III) and chromium(III) form very stable complexes with alkyl-N-iminodiacetic acids. The calcium(II)-methyl-N-iminodiacetate complex is octahedral in the solid state with most probably water in the remaining positions giving a mean Ca-O bond distance of ca. 2.36 angstrom. The iron(III) alkyl-N-iminodiacetate complexes have low solubility due to a strong tendency to form polymeric structures. Depending on pH in the solution at their preparation, the degree of hydrolysis in the resulting compound(s) may differ. In the solid state, the polymeric iron(III) alkyl-N-iminodiacetate compounds seem to have the mean composition Fe2O(C-x-IDA)(5); the mean Fe-O bond distances to the oxo group and the alkyl-N-iminodiacetate ligands are 1.92 and 2.02 angstrom, respectively. In these complexes the nitrogen atoms are bound at much longer bond distances, 0.1-0.2 angstrom, than the carboxylate oxygens. This distribution with short strong Fe-O bonds and much longer and weaker Fe-N bonds is also found in most other structurally characterized iron(III) carboxylated amine/polyamine complexes. The chromium(III) alkyl-N-iminodiacetate complexes are octahedral in both solution and solid state, and the low solubility of the solid compounds indicates a polymeric structure with the ligands bridging chromium(III) ions. Also, chromium(III) binds oxygen atoms in carboxylated amines at significantly shorter distance than the nitrogen stoms. The chromium(III) alkyl-N-iminodiacetate complexes display such slow kinetics at titration with strong base that the back-titration with strong acid shows completely different acid-base properties, thus the acid-base reactions are irreversible.

Authors/Creators:Lindblad, Cecilia and Cassel, Anders and Persson, Ingmar
Title:Complex Formation of Alkyl-N-iminodiacetic Acids and Hard Metal Ions in Aqueous Solution and Solid State
Series Name/Journal:Journal of Solution Chemistry
Year of publishing :2020
Page range:1250-1266
Number of Pages:17
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Physical Chemistry
Keywords:Alkyl-N-iminodiacetate, Calcium(II), Iron(III), Chromium(III), Complex formation, Structure
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Additional ID:
Type of IDID
Web of Science (WoS)000579318400001
ID Code:21976
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Molecular Sciences
Deposited By: SLUpub Connector
Deposited On:03 Feb 2021 10:43
Metadata Last Modified:12 Sep 2022 08:19

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