Comparative structural and spectral analyses for mononuclear and dinuclear metal complexes of 2-thiophen and 2-(5-bromothiophen) imidazo[4,5-f][1,10]phenanthroline

Abstract

A series of mononuclear and dinuclear mercury(I), mercury(II), nickel(II), lanthanum(III), ferrous(II) and ruthenium(II) complexes 4–11 with different metal/ligand molar ratios (1 : 1, 1 : 2 and 1 : 3), having 2-thiophenimidazo[4,5-f[[1,10[phenanthroline (TIP) and 2-(5-bromothiophen)imidazo[4,5-f][1,10[phenanthroline (5-Br-TIP) ligands, have been synthesized and structurally compared. In addition, three protonated salts of TIP and 5-Br-TIP (1–3) with PF₆⁻ and ClO₄⁻ counterions have been described herein where the proton is found to be located at one of the nitrogen atoms of 1,10-phenanthroline moiety. It is notable that the whole molecules of dinuclear mercury(I) and nickel(II) complexes 6 and 7 exhibit excellent planarity in the lengths of 2.52 and 2.90 nm, respectively. UV-Vis, ¹H NMR and luminescence spectra of ligands TIP and 5-Br-TIP, protonated salts 1–3 and metal complexes 4–11 have also been studied and compared.