Stability Constants of the Binary Complexes of Co(II), Ni(II), Cu(II) & Zn(II) with Thiamine & Ternary Complexes with Thiamine as Primary Ligand & Thymine or Uracil as Secondary Ligand

Abstract

Stability constants of the 1 : 1 and 1 : 2 metal-thiamine (vitamin B₁) complexes and 1: 1 : 1 metal-thiamine-thymine/uracil mixed ligand complexes have been determined in aqueous medium by potentiometric method at 35° ± 0.1°C and <em>μ </em>= 0.10 <em>M </em>(KNO₃). The <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0> log <em>K </em>values for 1:2 metal-thiamine systems are positive whereas values for 1: 1 : 1 metal-thiamine-thymine or -uracil systems are negative. So the <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0> log <em>K </em>values reveal that mixed ligand complexes are less stable than the binary (1:1) complexes.