Synthesis of Bis(pyrrole-carboxylate) Polymeric Complexes

This work covers the preparation and structural characterisation of four novel bis(pyrrole-carboxylate) ligands and their polymeric complexes. The synthesis of ligands was based on several synthetic routes. This includes the formation of pyrrole esters that reacted with the diamines precursors to give Schiff-bases. The reduction of Schiff-bases gave the appropriate secondary amine ester compounds, which hydrolised by LiOH to yield the title bis(pyrrole-carboxylate) ligands. The reaction of ligands with some metal ions resulted in the formation of polymeric complexes of the general formula [Cr(Ln)(H2O)2]Cl, [M(Ln)(H2O)4] and Li[Ag(Ln)(H2O)2] (M= Mn(II), Co(II), Ni(II) Cu(II), Zn(II) and Cd(II); Ln= L1-L4). Compounds were fully characterised by elemental analyses, melting points, FTIR, UV-Vis, magnetic susceptibility, NMR spectroscopy (1H-, 13C-, DEPT-13C,-1H-1H COSY and 1H-13C HQMC-NMR), mass spectroscopy, thermal analysis and X-ray single crystal determination. Physico-chemical characterisation indicated the formation of six coordinate structures around metal centre that contain coordinated water molecules and the carboxylato moieties adopt a syn-syn bridging coordination mode.