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

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 pH e 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.

The Interaction of Guest Molecules with Co‐MOF‐74: A Vis/NIR and Raman Approach

“…The spectra were normalized on the maximum around 1200 nm which can be assigned to the spin allowed d–d transition of cobalt and is typical for an octahedral Co II complex . The second absorption band around 600 nm also corresponds to the d–d transition of an octahedral Co II complex (see Supporting Information) . The last main absorption band at around 430 nm is assigned to the n–π* transition of the organic linker (see Supporting Information).…”

Vis/NIR‐ und Raman‐Untersuchung der Wechselwirkung von Gastmolekülen mit Co‐MOF‐74

“…Alle Spektren wurden zur besseren Vergleichbarkeit auf das Maximum bei λ =1200 nm normiert, das dem für oktaedrische Co II ‐Komplexe typischen, Spin‐erlaubten d‐d‐Übergang von Cobalt zugeordnet werden kann . Auch die Absorptionsbande um λ =600 nm kann dem d‐d‐Übergang eines oktaedrischen Co II ‐Komplexes zugeordnet werden (siehe SI) . Die letzte Hauptabsorptionsbande bei etwa λ =430 nm kann dem n‐π*‐Übergang des organischen Linkers zugeordnet werden (siehe SI).…”

Sulfonato Complex Formation Rather than Sulfonate Binding in the Extraction of Base Metals with 2,2′-Biimidazole: Extraction and Complexation Studies

“…The equatorial distances for the copper complex are Cu1-N11 and Cu-N11´ = 2.020(1) Å and Cu1-N13 and Cu1-N13´ = 2.0202(1) Å, while the axial Cu1-O21 and Cu1-O21´ distance is 2.430(1) Å. This is typical of a Jahn-Teller distorted copper(II) complex [15]. The majority of Cu(II) complexes are tetragonally distorted.…”

“…In this solvent-extraction system, the protonation, complexation and phase distribution equilibria can be used to describe the system quantitatively with respect to the distribution ratio of a metal ion (M n+ ), and provide information on the coordination numbers involved in the extraction reaction [15]. The chelating agent (L) must distribute between the organic and aqueous phases to result in complexation in the aqueous phase, and that distribution coefficient is represented by K D (L): In this solvent-extraction system, the protonation, complexation and phase distribution equilibria can be used to describe the system quantitatively with respect to the distribution ratio of a metal ion (M n+ ), and provide information on the coordination numbers involved in the extraction reaction [15]. The chelating agent (L) must distribute between the organic and aqueous phases to result in complexation in the aqueous phase, and that distribution coefficient is represented by KD(L):…”