Potentiometric and Theoretical Studies of Stability Constants of Glyoxime Derivatives and their Nickel, Copper, Cobalt and Zinc Complexes 

Hayati Sari,a* Muzaffer Can,a and Mustafa Macitb
a Gaziosmanpaºa University, Faculty of Art and Sciences, Department of Chemistry, 60250, Tokat, Turkey. E-mail: hsari@gop.edu.tr
Ondokuzmayıs University, Department of Chemistry, 55139 Samsun, Turkey

The dissociation constants of 1,2-bis(4-methylpiperazine)glyoxime (BMPGH2) and 1,2-bis(4-benzylpiperazine)glyoxime (BBPGH2) were determined in 0.1 mol dm–3 NaCl and 0.1 mol dm–3 HCl at 25 °C potentiometrically. pKa values of BMPGH2 and BBPGH2 were obtained as 2.91, 6.79, 7.97, 10.00 and 3.46, 5.89, 6.77, 9.76, respectively. The protonation order of nitrogen atoms in the BMPGH2 and BBPGH2 were determined using Semi-empirical AM1 method. In various pH conditions, the different complexes formulated as MH6L2, MH5L2, MH4L2, MH3L2, MH2L2, MHL2, ML2, MH–1L2, and MH–2L2 were formed with titration of ligand and Cu, Co, Ni and Zn ions.

Key words: 1,2-bis(4’-methylpiperazine)glyoxime, 1,2-bis(4’-benzylpiperazine)glyoxime, dissociation constant, stability constants, SUPERQUAD, AM1 method