Synthesis, structures, and magnetic properties of a family of 3d–4f [Na2Fe6Ln2] complexes (Ln = Y, Gd and Dy): effect of ligands on the connection of inorganic subunits

Abstract

A family of 3d–4f heterometallic compounds [Na₂Fe^III₆Dy^III₂(N₃)₄(HL)₄(CH₃O)₄(PhCO₂)₆] (1, H₄L = 2-{[(2-hydroxy-3-methoxyphenyl)methylene]amino}-2-(hydroxymethyl)-1,3-propanediol), [Na₂Fe^III₆Dy^III₂(N₃)₄(L′)₄(CH₃O)₄(PhCO₂)₆(H₂O)] (2, H₃L′ = (E)-2-ethyl-2-(2-hydroxy-3-methoxybenzylideneamino)propane-1,3-diol), [Na₂Fe^III₆Dy^III₂(N₃)₄(L′)₄(CH₃O)₄(Bu^tCO₂)₆] (3) [Na₂Fe^III₆Y^III₂(N₃)₄(L′)₄(CH₃O)₄(PhCO₂)₆(H₂O)] (4), and [Na₂Fe^III₆Gd^III₂(N₃)₄(L′)₄(CH₃O)₄(PhCO₂)₆(CH₃OH)₂] (5) have been prepared using Schiff-base ligands, trinuclear iron precursor complexes, azides and lanthanide nitrates as reactants. In compounds 1 and 2, the structure of the [Na₂Fe^III₆Dy^III₂] cluster forms a couple of cis,trans-isomers with substitution of methyl for a free hydroxyl group which belongs to the Schiff-base ligand. When the pivalates are employed instead of bulkier benzoates, the trans-[Na₂Fe^III₆Dy^III₂] clusters act as network nodes in the formation of rhombic grid-like layered structures in compound 3. Compounds 2, 4 and 5 have similar metallic cores, only with different crystal solvent molecules. The magnetic measurements on all the compounds indicate dominant antiferromagnetic interactions between the metal centers.