Neutron diffraction study of the magnetic structures of manganese succinate Mn(C4H4O4): A complex inorganic-organic framework

The antiferromagnetic structures of the Mn succinate framework, Mn(C4H4O4), have been determined using neutron diffraction. The structure comprises alternating layers containing chains of edge-sharing Mn(II)O-6 octahedra and sheets of corner-sharing Mn(II)O-6 octahedra, respectively, with a layer separation of similar to 7.5 angstrom. At 10 K the edge-sharing MnO6 octahedral chains order antiferromagnetically into a collinear sinusoidal spin structure with a propagation vector k(2)=(0,-0.5225,0), in which individual edge-sharing MnO6 chains are ferromagnetically ordered. The sheets of corner-sharing MnO6 octahedra order magnetically at 6 K, adopting the antiferromagnetic structure expected for a square arrangement of cations with a propagation vector k(8)=(-1, 0, 1). The ordering of these sheets at a lower temperature than the chains is consistent with their longer nearest-neighbor superexchange pathway. The magnetic structure of the edge-sharing layers is unaffected by the 6 K phase transition, indicating that the orderings of the two different layers are essentially independent of each other.