Five Disk‐Shaped {MII7} (M = Mn, Fe, Co, Cu, Zn) Clusters and One Capsule‐Like {CuII6NaI2} Cluster Assembled from the Same Schiff Base Ligand

Abstract

Six transition‐metal clusters of compositions [Mn7L6](NO3)2·2CH3OH (1), [Fe7L6](NO3)2·2CH3OH (2), [Co7L6](NO3)2·2CH3OH (3), [Cu7L6](NO3)2 (4), [Zn7L6](NO3)2·2CH3OH (5), and [Cu6Na2L6](NO3)2·4CH3OH (6) {H2L = 2‐(2‐hydroxy‐3‐methoxybenzylideneamino)phenol} have been synthesized under solvothermal conditions. The structures of 1–6 have been established based on single‐crystal X‐ray diffraction studies. Complexes 1–5 possess disk‐shaped {MII7} cores, with the central MII ion and the six peripheral MII ions being linked by six µ3‐O atoms. The six MII ions of the rim of the disk are bridged in a pairwise manner by six µ2‐O atoms. Complex 2 is a very rare example of a disk‐shaped {Fe7} cluster in which all of the Fe atoms exhibit +2 oxidation state. Furthermore, this is the first time that the five isostructural heptanuclear clusters were constructed by using an identical Schiff base ligand. The molecule of complex 6 contains a capsule‐like {Cu6Na2} core. In this core, two sodium ions reside on the two vertices of the capsule and the 12 vertices of the {Cu6O6} hexagonal prism are occupied by alternately arrayed six CuII ions and six O atoms. Photoluminescence studies suggest strong emission for 5 in the solid state at room temperature. Variable‐temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4 and 6. The ac susceptibility studies were also performed with 3. Strong out‐of‐phase, χ′′, signals were observed for 3 at zero field, suggesting that 3 is a class of single molecule magnet (SMM).