An Exploratory Study of Tridentate Amine Extractants: Solvent Extraction and Coordination Chemistry of Base Metals with Bis((1R-benzimidazol-2-yl)methyl)amine

Nomampondo P. Magwa, Eric Hosten, Gareth M. Watkins, Zenixole R. Tshentu

Department of Chemistry, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa.
Department of Chemistry, Rhodes University, Grahamstown, South Africa.

DOI: 10.4236/ijnm.2012.13007                

Abstract

Solvent extraction of base metals using bis((1-decylbenzimidazol-2-yl)methyl)amine (BDNNN) showed a lack of pH-metric separation of the metals. The extraction system was described quantitatively using the equilibria involved to derive the mathematical explanation for the two linear log D vs pHe plots for each metal ion extraction curve, and coordination numbers could also be extracted from the two slopes. The lack of separation was attributed to the absence of stereochemical “tailor making” since the complexes isolated from the reaction of the ligand, bis((1H-benzimidazol- 2-yl)methyl)amine (NNN), with base metals suggested the formation of similar octahedral complex species from spectral and crystal structure evidence. The bis tridentate coordination observed was in agreement with information extracted from the extraction data. This investigation opens up an opportunity and an approach for the evaluation of amines as extractants but cautions against tridentate ligands.

Keywords

Base Metals; Tridentate; Bis((1H-benzimidazol-2-yl)methyl)amine; Extractive and Coordination Chemistry

Conflicts of Interest

The authors declare no conflicts of interest.

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