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

Area of Science:

• Coordination Chemistry
• Materials Science
• Magnetochemistry

Background:

• Schiff-base ligands are versatile building blocks for constructing metal complexes.
• Heterometallic clusters and coordination polymers offer tunable magnetic properties.
• Understanding structure-property relationships in polynuclear metal systems is crucial.

Purpose of the Study:

• To synthesize and characterize novel trinuclear heterometallic clusters and quasi-1D coordination polymers.
• To investigate the structural differences and similarities between the cluster and the polymer.
• To explore the magnetic properties arising from distinct structural arrangements.

Main Methods:

• Solvothermal synthesis using iron(III) chloride, nickel(II) chloride, 2-hydroxynaphthaldehyde, and amino acids (glycine or methyl-alanine).
• Structural characterization of the resulting cluster and polymer using X-ray diffraction.
• Magnetic susceptibility measurements to determine magnetic interactions.

Main Results:

• Formation of a trinuclear heterometallic cluster [Fe2Ni(L1)4(MeOH)4] (1) and a quasi-1D coordination polymer {[Fe2Ni(L2)4(MeOH)2]n} (2).
• Complex 1 features a linear {Fe2Ni} trimetallic unit.
• Complex 2 consists of repeating linear {Fe2Ni} units forming a quasi-1D chain with dominant ferromagnetic interactions in complex 1 and antiferromagnetic interactions in complex 2.

Conclusions:

• The choice of amino acid ligand (glycine vs. methyl-alanine) dictates the formation of either a discrete cluster or a 1D polymer.
• Remarkable structural similarity exists between the repeating unit of the polymer and the discrete cluster.
• Significant differences in magnetic behavior (ferromagnetic vs. antiferromagnetic) arise from the distinct supramolecular arrangements.