Intramolecular interligand interaction in zinc(II) and cadmium(II) complexes involving bidentate and tridentate ligands

Abstract

The stability constants of complexes of the type (MAL) in aqueous medium have been determined potentiometrically at 25°C and ionic strength of 0.2 dm^{- 3} (NaClO₄) using SCOGS computer program [where M = Zn(II) or Cd(II), A= dipicolinic acid (dpa), iminodiacetic acid (imda) or diethylenetriamine (det), and L= <i>a</i>-alanine (ala), phenylalanine (phe), <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-tyrosine (tyr), <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-tryptyophan (trp), glycylglỳcine (gg), glycyl <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-alanine (ga), ethylenediamine (en)]. The stability of these complexes is discussed in terms of <img src='/image/spc_char/delta.gif' border=0>log <i>K </i> values and compared with those of analogous Cu(II) and Ni(ll) complexes. A penta-coordination in zinc(II) and cadmium(II) complexes is suggested.