Synthesis and Structural Studies on Polynuclear Metal Complexes Derived from a New Multidentate Ligand
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Date
2000-06
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Addis Ababa Universty
Abstract
This study presents the synthesis and characterization of a new multidentate ligand H6-DHADB
and its metal complexes. The ligand, H6-DHADB is a hydrated Schiff base product formed by
the condensation of2, 4- Dihydroxy-5-acetyl acetophenone (H,-DAA) and 1,3- diamino propane
in 3:2 mole ratio. It possesses four independent chelating sites (00, ONNO, ONNO, 00)
separated by bulky phenyl groups. The metal complexes of H6-DHADB with Co(II), Ni(ll),
Cu(ll), Zn(ll), Cd(Il) and Hg(lI) have been synthesized from methanolic media at pH ~8. They
have been characterized on the basis of elemental analysis, thermal, conductance, IR and
electronic spectral studies. The studies have shown that all the metal complexes are nonelectrolytes
with metal to ligand ratios in 3: 1,2: 1 and 2: I in Co(ll), Ni(Il) and Cu(ll) complexes
respectively and 4: I, 2: I, 1: 1 in Zn(ll), Cd(Il) and Hg(ll) complexes respectively. Based on
IR spectral data, a variety of donor propel1ies of the ligand has been proposed. ONNO, ONNO
and 00 chelation with cobalt(II); 00 and 00 chelation with nickel(II); ONNO and ONNO
chelation with copper(II); 00, ONNO and 00 chelation with zinc (II) and 00 chelation with
Cd(ll) and Hg(lI) have been suggested.
Based on electronic spectral data cobalt(ll) complex exhibited octahedral, copper(Il) complex
shows square planar structure and nickel(ll), zinc(Il), cadmuim(ll) and mercury(ll) complexes
attain tetrahedral geometries.
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Keywords
Multidentate Ligand