Studies on equilibrium constants of binary and ternary complexes of 3-hydroxyquinazolin- 2,4(3H)-dione with CoII, NiII, CuII and znII at different temperatures

Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University, Hyderabad-500 072, India Department of Chemistry, University College of Engineering, Osmania University, Hyderabad-500 007, India E-mail : satyambchem@yahoo.co.in narayana satya 1969@yahoo. co. in Manuscript received 23 March 2005, revised 2 January 2006, accepted 23 March 2006 The stability constants or 1 : 1 and 1 : 2 binary Mll-HQDO and ternary [Mll-HQDO-A] chelates [where Mll = Coll, Nill, Cull and Znll; HQDO = 3-bydroxyquinazolin-2,4(3\(H\))-dione, A = glycine (gly), \(a\)-alanine (ala), proline (pro), histidine (hist), iminodiacetic acid (IMDA), nitrilotriacetic acid (NTA), 2,2'-bipyridyl (bipy) and ethylenediamine (en)] have been determined pH-metrically in 10% (v/v) aqueous ethanol medium at 20, 30 and 40 °C and I = 0.1 M KNO3. The order of formation constants of binary as well as ternary chelates are coll Znll. The formation of binary complexes are more favourable over ternary complexes. The thermodynamic parameters were evaluated