Switching on Single‐Molecule‐Magnet Behavior in Mn III –Schiff Base Out‐of‐Plane Dimers by the Phosphonate Terminal Ligand

This paper reports two metal phosphonate clusters containing Mn III –Schiff base units, namely, [Mn 2 (5‐Brsalen) 2 (C 10 H 7 PO 3 H) 2 ] · 2CH 3 OH ( 1 ) and [Mn 6 (5‐Brsalen) 6 (C 10 H 7 PO 3 ) 2 (H 2 O) 2 ](ClO 4 ) 2 · 7.6H 2 O ( 2 ) [5‐Brsalen = N , N′ ‐ethylenebis(5‐bromosalicylideneiminate) dianion]. Compound 1 shows a discrete dinuclear structure in which dimers of Mn 2 (5‐Brsalen) 2 are terminated by the naphthylphosphonate ligand. In 2 , each naphthylphosphonate ligand connects three Mn atoms, forming triangular units of {Mn 3 PO 3 }, which are further cross‐linked through phenoxide oxygen atoms into a hexanuclear cluster. Magnetic studies reveal that the exchange couplings mediated through the phenoxide bridges within the dimer are ferromagnetic in compounds 1 and 2 . Further, slow magnetization relaxation, characteristic of single‐molecule magnets (SMMs), is observed in both 1 and 2 , in contrast to the non‐SMM behavior in the precursor of [Mn(5‐Brsalen)(H 2 O)] 2 (ClO 4 ) 2 .