Spin Coupling and Magnetic Anisotropy in 1D Complexes with Manganese(III) Units and Carboxylate Bridges. Synthesis and Analysis, Calculations and Models.
We report the synthesis, structure and magnetic properties of a series of Mn(III) complexes based on 5MeO‐salen, N,N'‐ethylenebis(5‐methoxysalicylideneiminate), and acetate ligands, namely [Mn2(5MeO‐salen)2(CH3COO)]X, X=ClO4‐ (1), PF6‐(2) , CF3SO3‐(3). The [Mn(5MeO‐salen)]+ form oxo‐bridged dimers whose further assembling by acetate groups, leads to zigzag chains. There are two alternating types of dimeric {Mn2O2} units, each of them intrinsically ferromagnetic and anisotropic, but mutually coupled antiferromagneticaly along the chain. Magneto‐structural analyses were carried out with the help of ab initio calculations, understanding the subtle factors of local magnetic anisotropy combined with the exchange effects. A qualitative mechanism of the exchange coupling was advanced, in the continuation of ab initio calculations, explaining the ferromagnetism inside the phenoxo‐bridgend dimer units and the antiferro behaviour of the acetate bridge.