Synthesis, crystal structures and properties of three glutarato and adipato bridged manganese(II) coordination polymers under ambient conditions

Three Mn(II) polymers Mn(H2O)4(C5H6O4) 1, [Mn(H2O)2(C5H6O4)]·H2O 2 and Mn(H2O)(C6H8O4) 3 were synthesized (H2(C5H6O4) = glutaric acid, H2(C6H8O4) = adipic acid) under mild ambient conditions. The [Mn(H2O)2]2+ units in 2 are interlinked by the glutarate anions with a η4μ3 bridging mode to form 2D (4·82) topological networks, which are stacked via interlayer hydrogen bonds into a 3D (43·65·82)(47·63) topological net. Compound 3 crystallizes in the acentric space group P21 and exhibits significant ferroelectricity (remnant polarization Pr = 0.371 nC cm−2, coercive field Ec = 0.028 kV cm−1, saturation of the spontaneous polarization Ps = 0.972 nC cm−2). The adjacent MnO6 octahedrons in 3 are one atom-shared to generate the Mn2O11 bi-octahedron, leading into 1D metal oxide chains. The resulting chains are interconnected by the η5μ5 adipate anions to form new 2D (48·62) networks, which are held together via strong interlayer hydrogen bonds into 3D α-Po topological supra-molecular architecture. The temperature-dependent magnetic susceptibility data of 1–3 shows overall anti-ferromagnetic interactions between the metal ions bridged by the carboxylate groups.