The coordination and extractive chemistry of the later 3d transition metals with bis((1R-benzimidazol-2-yl)methyl)sulfide

Abstract

The coordination chemistry of the later 3d metal ions with bis((1H-benzimidazol-2-yl)methyl)sulfide (NSN) is investigated. All the complexes had general formula [M(NSN)2]X yH2O, where M = Co(II), Ni(II), Cu(II), and Zn(II), ) or , and y = 2–5. The infrared and conductivity measurements provided evidence that the sulfate and sulfonate acted as counter anions in the isolation of these dicationic complexes. X-ray crystal structures of [Co(NSN)2](RSO3)2 4H2O and [Ni(NSN)2](RSO3)2 2H2O revealed a distorted octahedral geometry for these complexes. Extraction studies showed a lack of pH-metric separation of the later 3d metal ions with bis((1-octylbenzimidazol-2-yl)methyl)sulfide (BONSN) as an extractant, but that extractions occurred in the low pH range with an opportunity for back-extraction. This investigation suggests that tridentate ligands (of the nature investigated) are not feasible extractants for metal ions due to their lack of stereochemical “tailor making.”