Molar Conductometric and Stepwise Potentiometric Studies on Chromium(III)-, Manganese(II)-, Copper(II)-, and Silver(I)- 2,2'Dipyridyl-Salicylaldoxime-Benzamide Complexes

Abstract

Molar conductivity titrations and conductometric measurements as well as pH-metric studies were done on Cr(III), Mn(II), Cu(II), and Ag(I) with 2,2'-dipyridyl (Dipy), salicylaldoxime (SD) and benzamide (BAM) at 35 ºC and 45 ºC. Conductivity and potentiometry studies indicated the formation of 1:1, 1:2 and 1:3 Cr(III)-, Mn(II) and Cu(II)-, and 1:1 and 1:2 Ag(I)-Dipy or BAM, 1:1 and 1:2 Cr(III)-, Mn(II)-, Cu(II)-, and Ag(I)-SD, 1:1:1 Cr(III)-, Mn(II)-, Cu(II)-, Mn(II) Cu(II)- and Ag(I)-SD, 1:1:1 Cr(III)-, Mn(II)-,Cu(II)- and Ag(I)-Dipy-SD, Dipy-BAM and SD-BAM and 1:1:1:1 Cr(III)-, Mn(II)-, Cu(II)-, and Ag(I)-Dipy-SD-BAB complexes. Complexation takes place through two coordinate bonds between the metal ions and the two nitrogen atoms of Dipy, two covalent bonds between the metal ions and the phenolic OH and oximic OH groups of salicyladoxime, and coordinated and covalent bonds between the metal ions and the benzoyl CO and amide NH groups of BAM. Proton-ligand and metal ligand(s) conditional stability constants at 35 and 45 ºC were estimated. Thermodynamic parameters (∆ºG, ∆H, ∆S) at 35 and 45 ºC of binary, ternary and quaternary complexes were evaluated.