Slow magnetic relaxation in OSeO bridged manganese() Schiff base complexes

Two new chain complexes consisting of a Mn(salen) building block bridged by OSeO units, [Mn 2 (salen) 2 (L)](ClO 4 ) ( 1 ) and {[Mn(salen)] 2 (L) 2 }Y ( 2 ) (salen = N , N -bis(salicylidene)-ethylenediamine, L = 3,4,5-trifluorobenzeneseleninic acid, Y = salicylaldehyde) have been synthesized and characterized structurally and magnetically. In the two complexes above, the 3,4,5-trifluorobenzeneseleninic acid ligand adopts a syn anti bridging coordination mode and all the Mn III ions show a distorted octahedral geometry. In complex 1 , the [Mn 2 (salen) 2 ] 2+ dimers are connected alternatively by the bridging ligands into an infinite zigzag chain, while the [Mn(salen)] + monomers are connected alternatively in complex 2 . The magnetic measurements reveal that both complexes exhibit slow magnetic relaxation behaviours with an effective energy barrier U eff = 31.2 K for 1 and U eff = 35.1 K for 2 , respectively. These compounds are rare examples of a small number of aromatic selenite based magnetic materials. Two new chain complexes consisting of a Mn(salen) building block bridged by OSeO units, [Mn 2 (salen) 2 (L)](ClO 4 ) ( 1 ) and {[Mn(salen)] 2 (L) 2 }Y ( 2 ) (salen = N , N -bis(salicylidene)-ethylenediamine, L = 3,4,5-trifluorobenzeneseleninic acid, Y = salicylaldehyde) have been synthesized and characterized structurally and magnetically.