A Linear {Fe III 2 Ni II } Cluster, a Structurally Closely Related Quasi 1D {Fe III 2 Ni II } Chain

The solvothermal reaction between FeCl₃·6H₂O, NiCl₂·6H₂O, 2-hydroxynaphthaldehyde, and glycine (gly) in MeOH results in the formation of the trinuclear heterometallic cluster [Fe^ΙΙΙ ₂Ni^ΙΙ(L₁)₄(MeOH)₄] (1) in good yield, while the same reaction upon replacing gly with methyl-alanine (mAla), results in the formation of the closely related quasi 1D coordination polymer {[Fe^ΙΙΙ ₂Ni^ΙΙ(L₂)₄(MeOH)₂]_n} (2) (L₁, L₂: the dianionic form of the Schiff-base ligand derived from the condensation of 2-hydroxynaphthaldehyde and gly (L₁ for 1), or mAla (L₂ for 2)). The structure of 1 describes a linear trimetallic {Fe^III ₂Ni} unit, whereas complex 2 consists of repeating linear {Fe^III ₂Ni} units with each one connected to two neighboring units via four coordination bonds, forming a quasi-1D chain. The structural similarity between complex 1 and the repeating unit of complex 2 is remarkable. However, their magnetic properties differ significantly, with complex 1 displaying dominant ferromagnetic interactions, and complex 2 showing antiferromagnetic interactions.