N-(Diisopropylthiophosphoryl)-N′-(R)-thioureas: synthesis, characterization, crystal structures and competitive bulk liquid membrane transport of some metal ions

Abstract

Ten N-thiophosphorylated thioureas of the common formula RC(S)NHP(S)(OiPr)₂ [R = iPrNH (1), EtNH (2), Et₂N (3), 2,5-Me₂C₆H₃NH (4), 4-Me₂NC₆H₄NH (5), 2-MeO(O)CC₆H₄NH (6), 2-PyNH (7), 2-PyCH₂NH (8), 3-PyCH₂NH (9), cyclo-C₂H₂N₃NH (10)] have been synthesized and characterized by IR, NMR spectroscopy and elemental analysis. Molecular structures of 1 and 4–8 were elucidated by X-ray diffraction revealing linear, bi- or trifurcated intramolecular hydrogen bonds. Additionally, their crystal structures are stabillized by two intermolecular hydrogen bonds, which in turn lead to a centrosymmetric dimer formation. The hydrogen bonded dimers of 5–8 are packed to polymeric chains through the π⋯π stacking interactions between aryl or pyridyl rings. Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using 2–6 and 8–10 as the ionophore present in the organic phase. The source phase contained equimolar concentrations of Co^II, Ni^II, Cu^II, Zn^II, Ag^I, Cd^II and Pb^II with the source and receiving phases being buffered at pH = 5.5 and 1.0, respectively. The obtained data were compared with the transport and extraction properties of 1 and 7, which were described recently.