One-dimensional manganese(III) and iron(III) coordination polymers assembled by N < inf > 2 < /inf > O < inf > 2 < /inf > -donor Schiff bases and 4,4′-bipyridine: syntheses, structures and properties

Abstract

Reactions of Mn(ClO4)2·6H2O and Fe(ClO4)3·6H2O with the tetradentate N2O2-donor Schiff bases N,N′-bis(salicylidene)-ortho-phenylenediamine and N,N′-bis(salicylidene)ethylenediamine (H2salophen and H2salen, where 2 Hs represent the two dissociable phenolic protons), respectively and the bridging ligand 4,4′-bipyridine (bipy) in presence of triethyl amine in methanol under ambient conditions produce one dimensional coordination polymers {[Mn(salophen)(μ-bipy)]ClO4}n (1) and {[Fe(salen)(μ-bipy)]ClO4}n (2) in ~60% yields. Both complexes have been characterized by elemental analysis and spectroscopic (IR and DR) measurements. The linear polymeric structures of 1 and 2 have been confirmed by single-crystal X-ray crystallography. The metal centres in these polymers are in distorted octahedral N4O2 coordination spheres. Each of the two dibasic tetradentate ligands (salophen2– and salen2–) forms an ONNO square-plane around the metal centre, while the two axial coordination sites are occupied by N-atoms of the two bridging bipy ligands. Variable temperature magnetic susceptibility measurements reveal the high-spin configuration of manganese(III) and iron(III) and Curie paramagnetic behaviour of each of the two coordination polymers. Graphical abstract: Facile one-pot syntheses of two new one-dimensional coordination polymers {[Mn(salophen)(μ-bipy)]ClO4}n and {[Fe(salen)(μ-bipy)]ClO4}n have been described. Both polymers were characterised by elemental analyses and solid state spectroscopic and cryomagnetic measurements. Linear chain-like structures of the high-spin Mn(III) and Fe(III) containing Curie paramagnetic polymers were confirmed by single crystal X-ray crystallography. [Figure not available: see fulltext.]