Solution Studies on Co(II), Ni(II), Cu(II), and Zn(II) Complexes of Hexamethylenetetramine in Aqueous and Non-Aqueous Solvents

Figure 4

Titration curves of the HMTA ligand alone and of the HMTA-M²⁺ systems with HNO₃  5×10⁻² mol⋅L⁻¹ (M = Co, Ni, Cu, or Zn; 𝐶_M = 5×10⁻³ mol⋅L⁻¹ and 𝐶_L=5×10⁻² mol⋅L⁻¹, I = 0.1, T = 25°C).