Synthesis and characterisation of 5,6- bis(salicylideneimino )-1,10-phenanthroline and its trinuclear complexes

Abstract

As a multidonor ligand with phenanthroline and salicylaldimine functionalities on the same molecule, 5,6-bis(salicylideneimino)-1,10-phenanthroline (LH₂) has been

synthesized by the reaction of 5,6-diamino-1,10-phenanthroline with salicylaldehyde and its metal complexes with Ni(II) and Cu(II) have been prepared. Both of the isolated complexes are trinuclear with metal ligand ratio of 3:2. Protonation constants of LH₂ which have been determined by potentiometric titration in solution are log <i>K</i>_{<span style="mso-bidi-font-style:italic">1</span>}<i>=</i><span style="mso-bidi-font-style:italic">8.96<i>, </i>log <i>K</i>_{<span style="mso-bidi-font-style:italic">2</span>}<i>=</i><span style="mso-bidi-font-style:italic">15. 88<i>, </i>log <i>K</i>_{<span style="mso-bidi-font-style:italic">3</span>}<i>=</i><span style="mso-bidi-font-style:italic">8.73<i> </i>and log <i>K</i>_{<span style="mso-bidi-font-style:italic">4</span>}<i>=</i><span style="mso-bidi-font-style:italic">2.78<i>. </i>The newly synthesized compounds have been verified by IR, ¹H NMR and mass spectra together with elemental analysis.

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