Modification of the structure and magnetic properties of fumarato-bridged Mn coordination polymers through different dimethyl-2,20-bipyridine co-ligands

Abstract

Abstract Manganese coordination polymers {Mn(- fum)(5dmb)(H2O)2}n (1) and {[Mn2(fum)2(4dmb)2] H2O}n (2) (fum= fumarato; 5dmb = 5,50-dimethyl-2,20-bipyridine; 4dmb = 4,40-dimethyl-2,20-bipyridine) were obtained from one-pot, solution reactions under ambient conditions. The fum ligand acquires different coordination modes in the presence of the different dmb ancillary ligands, promoting distinctive crystal structures, including divergent dimensionalities. Thus, X-ray single-crystal data reveal that complex 1 crystallizes in a monoclinic system with C2/c space group and forms an infinite one-dimensional polymer. The Mn(II) center is six-coordinated and displays a distorted octahedral configuration. In addition, the solid-state selfassembly of the polymeric structure of 1 gives rise to a twodimensional (2D) supramolecular framework, mainly through hydrogen bonding. In contrast, complex 2 crystallizes in a monoclinic system with a Cc space group and forms an infinite 2D coordination polymer having dinuclear units. The Mn(II) center has a distorted octahedral configuration. The thermal stabilities of both coordination polymers were investigated. Variable-temperature magnetic measurements show that complex 1 is paramagnetic, while complex 2 exhibits weak antiferromagnetic coupling between adjacent Mn(II) centers.