Syntheses, structures and magnetic properties of two mixed-valent disc-like hepta-nuclear compounds of [FeIIFeIII6(tea)6](ClO4)2 and [MnII3MnIII4(nmdea)6(N3)6]•CH3OH (tea = N(CH2CH2O)33-, nmdea = CH3N(CH2CH2O)22-)

Two mixed-valent disc-like hepta-nuclear compounds of [(FeFe6III)-Fe-II(tea)(6)](ClO4)(2) (1Fe, tea = N(CH2CH2O)(3)(3-)) and [(Mn3Mn4III)-Mn-II(nmdea)(6)(N-3)(6)]center dot CH3OH (2Mn, nmdea = CH3N(CH2CH2O)(2)(2-)) have been synthesized by the reaction of Fe(ClO4)(2) center dot 6H(2)O with triethanolamine (H(3)tea) for the former and reaction of Mn(ClO4)(2) center dot 6H(2)O with diethanolamine (H(2)nmdea) and NaN3 for the later, respectively. 1Fe has the cationic cluster with a planar [(FeFe6III)-Fe-II] core consisting of one central Fe-II and six rim Fe-III. atoms in hexagonal arrangement. The Fe ions are linked by the oxo-bridges from the alcohol arms in the manner of edge-sharing of their coordination octahedra. 2Mn is a neutral Cluster with a [(Mn3Mn4III)-Mn-II] core possessing one central M-II atom surrounded by six rim Mn ions, two Mn-II and four Mn-III. The structure is similar to 1Fe but involves six terminal azido ligands, each coordinate one rim Mn ion. 1Fe showed dominant antiferromagnetic interaction within the cluster and long-range ordering at 2.7 K. The cluster probably has a ground state of low spin of S = 5/2 or 4/2. The long-range ordering is weak ferromagnetic, showing small hysteresis with a remnant magnetization of 0.3 N beta and a coercive field of 40 Oe. Moreover, the isofield of lines 1Fe are far from superposition, indicating the presence of significant zero-field splitting. Ferromagnetic interactions are dominant in 2Mn. An intermediate spin ground state 25/2 is observed at low field. In high field of 50 kOe, the energetically lowest state is given by the m(s) = 31/2 component of the S = 31/2 multiplet due to the Zeeman effect. Despite of the large ground state, no single-molecule magnet behavior was found above 2 K.