Solution equilibrium study of the complexation of Co(II) and Zn(II) with nicotinaldehyde thiosemicarbazone

Abstract

The interaction of nicotinaldehyde thiosemicarbazone with Co(II) and Zn(II) was investigated in SDS-water(1.15%w/v) at 303K and ionic strength of 0.1 mol dm^–3. The speciation and stability constants of the metal complexes formed were determined by pH- metric method. Protonated and simple mononuclear species in different protonation and deprotonation states were identified. The corresponding formation constants calculated using MINIQUAD-75 computer program, and species distribution diagrams produced using the HYSS computer program. Selection of the best-fit chemical models was based on statistical parameters. The results obtained from the study revealed that, the NTSC on interaction with metal ions in solution, a series of mononuclear [M(LH_h)] (h = 1, 0), and bis- mononuclear [M(L₂H_h)] (h = 2, 1, 0,) species were identified.

Keywords: Formation constant, Nicotinaldehyde thiosemicarbazone, Metal complexes