Structural diversity in manganese squarate frameworks using N,N-donor chelating/bridging ligands: Syntheses, crystal structures and magnetic properties

Three new polymeric squarato-bridged manganese complexes {[Mn(H 2O)2(bpe)(sq)]·bpe·H2O} n (1), [Mn2(H2O)4(phen) 2(sq)2]n (2) and [Mn2(H 2O)2(phen)4(sq)]·(sq)·8(H 2O) (3) [bpe, 1,2-bis(4-pyridyl)ethane; phen, 1,10-phenanthroline; sq, squarate dianion] have been synthesized and characterized by single crystal X-ray diffraction analysis and variable temperature magnetic studies. Complex 1 is a 2D rectangular grid-like structure, achieved through flexible bpe bridging ligands and squarate dianions. On the other hand the use of chelating phen instead of bpe gives rise to a 1D polymeric chain in complex 2 and to a dinuclear entity in 3. In all the three complexes weak interactions play a vital role in stabilizing the solid-state structure. Variable temperature (2-300 K) magnetic studies indicate weak antiferromagnetic coupling between the metal centres in all the complexes. © The Royal Society of Chemistry 2006.