Potentiometric studies of Ni(II), Co(II) and Zn(II) metal ions with salicyloyl hydrazide and some O-O, N-N and N-O donor ligands

Abstract

Binary and ternary complexes of Ni(II), Co(II), Zn(II) metal ions with salicyloyl hydrazide (SAH) and alanine (ala), catechol (cat), 2,2'-bipyridyl (2,2'-bipy) and ethylenediamine (en) have been studied in solution by potentiometric technique at 30ᵒC and at ionic strength of 0.1<em> M </em> (KNO₃). The tridentate nature of salicyloyl hydrazide is established and this is further confirmed by IR studies of solid Ni(II)-SAH complex prepared. The stabilities in ternary complexes have been discussed in terms of ligand-ligand interactions, steric statistical and charge neutralization factors. The stabilisation is expressed in terms of <img src='/image/spc_char/delta.gif' border=0> log <em>K. </em> The <img src='/image/spc_char/delta.gif' border=0> log <em>K </em> values and percentage species computed gave parallel evidence for the stabilisation of ternary complexes.