Heterobinuclear complex formation by iminodiacetic acid and <img src='http://www.niscair.res.in/jinfo/smaller.gif' border=0><img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-2,3-diaminopropionic acid with some transition metal ions - Part I

Abstract

The heterobinuclear complexes formed by (i) iminodiacetic acid (imda) with Cu^II- Zn^II and Ni^II-Zn^IIand (ii) DL-2,3-diaminopropionic acid (dapa) with Cu^II-Ni^II and Cu^II-Zn^II have been investigated in biologically relevant conditions and the relevant stability constants have been evaluated using computer techniques. Two types of heterobinuclear complexes MAM' and MA₂M' have been detected. The stabilities of CuAZn and CuA₂Zn species in the Cu^II-imda-Zn^II system are higher than the stabilities of the species NiAZn and NiA₂Zn in the Ni^II-imda-Zn^II system. This is in accordance with the Irving-Williams order of stabilites. However the log<em>β</em>_CuANi and log<em>β</em>_CuA₂_Ni values in the Cu^II-dapa-Ni^IIsystem are found to be comparable to log<em>β</em>_CuAZn and log<em>β</em>_CuA₂_Zn in the Cu^II-dapa-Zn^II system which is not expected according to Irving-Williams order of stabilities. The probable reason for this and so the possible structures of the above heterobinuclear complexes are discussed.