Synthesis, crystal structures and properties of four manganese coordination polymers with 4,4-bipyridine-derived ligands

Four new coordination polymers, namely Mn2(4,4-bpy)2(o-tol)41, Mn2(4,4-bpy)2(m-tol)42, Mn2(bpp)2(m-tol)43 and {[Mn2(4,4-bpy)2(p-tol)4][Mn(4,4-bpy)2(H2O)2(p-tol)2]}·6H2O 4 have been synthesized from 4,4′-bipyridine (4,4-bpy), 1,3-bis(4-pyridyl)-propane (bpp), o-toluic acid (o-Htol), m-toluic acid (m-Htol) and p-toluic acid (p-Htol). All four complexes feature dinuclear Mn2(tol)4 moieties, which are bridged by 4,4-bpy or bpp ligands to form 1D double-chain structures. The resulted 1D double-chains are assembled via hydrogen bonding or π···π stacking into 2D supramolecular layers. The complexes were characterized by physico-chemical (thermal behavior) and infrared spectroscopy. Variable temperature magnetic characterization suggest weak antiferromagnetic coupling exchange between dimeric Mn(II) centers (J = −0.46 cm−1 for 1, −0.56 cm−1 for 2, −1.28 cm−1 for 3 and −0.59 cm−1 for 4).