Syntheses, crystal structures and magnetic properties of a novel family of penta-manganese complexes derived from an assembly system containing polydentate hydroxy-rich Schiff-base ligands.

The syntheses, crystal structures, and magnetochemical characterization are reported of a novel family of four pentanuclear manganese complexes, namely, [Mn(III)(5)(mu(3)-O)(2)(L(1))(4)(O(2)CMe)(3)(CH(3)OH)].1.5CH(3)OH.2.5H(2)O (1), [Mn(III)(5)(mu(3)-O)(2)(L(1))(4)(O(2)CPh)(3)(CH(3)OH)].2CH(3)OH.2.25CH(3)CN.1.5H(2)O (), [Mn(II)Mn(III)(4)(HL(2))(2)(L(2))(2)(O(2)C Me)(4))].CH(3)OH.H(2)O (3) and [Mn(II)Mn(III)(4)(HL(2))(2)(L(2))(2)(O(2)CPh)(4))].1.5H(2)O (4), where H(2)L(1) is 3,5-dibromosalicylidene-2-ethanolamine and H(3)L(2) is 3-(2-hydroxy-3,5-dibromobenzylideneamino)propane-1,2-diol. All the complexes can be obtained from a reaction system containing the trinuclear species Mn(3)O(O(2)CR)(6)(Py)(3) (R = Me or Ph) and H(2)L(1) or H(3)L(2) with similar procedures. Both cores in complexes 1 and 2 feature two mu(3)-O(2-) atoms, four L(1)(2-) ligands together with three RCO(2)(-) groups (R = Me or Ph) bridging five Mn(III) atoms to form an incomplete cubane extended at one face by an incomplete adamantane unit, which is an unprecedented structural type in Mn chemistry. Complexes 3 and 4 both have a rare Mn(II)Mn(III)(4)(mu(2)-O(alkoxide))(6) core, which can be regarded as two {Mn(II)Mn(III)(2)(mu(2)-O(alkoxide))(3)} scalene triangles, sharing the Mn(II) vertex. The dc magnetic susceptibility studies in the 2-300 K range for complexes 1-4 reveal the presence of overall antiferromagnetic intracluster interactions. A simple 3-J model was found to be adequate to describe the variable-temperature dc susceptibility data of complexes 1-4. The results have allowed us to compare the obtained magnetic exchange with magneto-structural correlations found previously for manganese-oxo clusters.