Study of some mixed ligand complexes of tertiary diimines and bidentate amide ligands

Abstract

Stability constants of the ternary complexes of copper(II) with tertiary diimines [bis(2-pyridylamine)(A¹) and 5-nitro-l, 10-phenanthroline (A²)] as primary ligands and bidentate amides [MeCOCH₂CONHPh (HL¹), MeCOCH₂CONHC₆H₄Me-(<em>o</em>) (HL²), MeCOCH₂CONHC₆H₄OMe-(<em>o</em>) (HL³), PhCOCH₂CONHPh (HL⁴), salicylamide (HL⁵), salicylanilide (HL⁶) and 5-bromosalicylamide (HL⁷)] as secondary ligands have been determined by potentiometric titrations at 30&deg;C in 50% (v/v) aqueous dioxane at 0.2 <em>M </em>[NaClO₄]. The log KMAL values have been determined using the computer programme SCOGS. The complexes have been isolated in solid state and characterized by elemental analyses, conductivity and magnetic measurements and electronic and IR spectral studies. The order of stabilization in the ternary complexes (i.e. <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0>log <em>K= </em>log <em>K</em><img src="http://www.niscair.res.in/jinfo/equation108.gif" alt="" border="0" /> - log <em>K</em><img src="http://www.niscair.res.in/jinfo/equation109.gif" alt="" border="0" /> values) has been explained on the basis of the electron repulsion concept. This has also been correlated with the shift in energy of the ligand field transition in the ternary complexes from the average value for the corresponding binary complexes.