Low Temperature Neutron Diffraction Studies in [Mn3(suc)2(ina)2]n: An Homometallic Molecular 3D Ferrimagnet

Neutron diffraction techniques have been used to determine the low temperature crystal structure and to shed light on the magnetic behavior of the [Mn-3(suc)(2)(ina)(2)](n), (suc = succinate and ma = isonicotinate) complex. The ferromagnetic signal observed below T-c approximate to 5 K in this compound is due to a noncompensation of homometallic spins in the 3D framework. The Mn(II) magnetic moments obtained from neutron diffraction refinements are slightly lower than those observed for isolated Mn(II) ions; this can be due to covalent spin delocalization or geometrical magnetic fluctuations. A small discrepancy between the value of the magnetic moments of each Mn(II) site is also observed [Mn(1) 4.1(2) mu(B) and the Mn(2) 3.9(1) mu(B)]. These differences between the theoretical and observed manganese magnetic moments are not unexpected in this large spin metal complex, and qualitatively reasonable given the synergistic interaction between the metal ions through oxo-bridge. The competition among different interactions, principally those covalent through organic ligands and dipolar interaction, drive to a final 3D ferrimagnetic order.