Ferromagnetic manganese "cubes": from PSII to single-molecule magnets

The reaction of Mn(O?CMe)?·2H?O with Me-saoH? (Me-saoH? = 2-hydroxyphenylethanone oxime) in MeCN forms the complex Mn(III)?(Me-sao)?(Me-saoH)?] (1) in good yields. Replacing Me-saoH? with Naphth-saoH? (Naphth-saoH? = 2-hydroxy-1-napthaldoxime) in the presence of CH?ONa forms the complex Mn(III)?(Naphth-sao)?(Naphth-saoH)?] (2) in low yields, while the reaction between Mn(ClO?)?·6H?O, Et-saoH? (Et-saoH?= 2-hydroxypropiophenone oxime) and NBu?OH in MeCN gives the complex Mn(III)?(Et-sao)?(Et-saoH)?] (3) in moderate yields. All three tetrametallic cages exclusively contain Mn(III) centres arranged in a "cube"-like topology, in which the metal centres are connected by -N-O(oximate) groups. The magnetic properties of 1-3 are near identical, revealing the presence of only ferromagnetic interactions between the metal ions leading to high-spin ground states of S = 8. The complexes display frequency dependent out-of-phase signals in ac susceptibility studies and, in the case of 1 single-molecule magnetism has been observed by means of single-crystal hysteresis loop measurements.